Tunneling field effect transistors

ABSTRACT

Disclosed herein are tunneling field effect transistors (TFETs), and related methods and computing devices. In some embodiments, a TFET may include: a first source/drain material having a p-type conductivity; a second source/drain material having an n-type conductivity; a channel material at least partially between the first source/drain material and the second source/drain material, wherein the channel material has a first side face and a second side face opposite the first side face; and a gate above the channel material, on the first side face, and on the second side face.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation (and claims benefit of priority under35 U.S.C. § 120) of U.S. application Ser. No. 16/632,266, filed Jan. 17,2020, entitled “TUNNELING FIELD EFFECT TRANSISTORS,” which is a nationalstage application under 35 U.S.C. § 371 of PCT International ApplicationSerial No. PCT/US2017/047523, filed on Aug. 18, 2017, entitled“TUNNELING FIELD EFFECT TRANSISTORS,” which are hereby incorporated byreference in their entirety.

BACKGROUND

One characteristic of a field effect transistor is its subthresholdswing, the gate voltage required to increase the drain current by afactor of ten. In conventional metal oxide semiconductor field effecttransistors (MOSFETs), the subthreshold swing may be greater than orequal to approximately 60 millivolts/decade of current, limited bythermionic emission.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example, not by way oflimitation, in the figures of the accompanying drawings.

FIGS. 1A-1E, 2A-2D, 3A-3D, 4A-4D, 5A-5D, 6A-6D, 7A-7D, 8A-8D, 9A-9D, and10A-10E are views of various embodiments of a tunneling field effecttransistor (TFET).

FIGS. 11A-11D, 12A-12D, 13A-13D, 14A-14D, 15A-15D, 16A-16D, 17A-17D,18A-18D, 19A-19D, 20A-20D, 21A-21D, 22A-22D, and 23A-23D are variousviews of assemblies in different stages of the manufacture of a TFET, inaccordance with various embodiments.

FIG. 24 is a flow diagram of an example method of manufacturing a TFET,in accordance with various embodiments.

FIG. 25 is a top view of a wafer and dies that may include a TFET, inaccordance with any of the embodiments disclosed herein.

FIG. 26 is a cross-sectional side view of an integrated circuit (IC)device that may include a TFET, in accordance with any of theembodiments disclosed herein.

FIG. 27 is a cross-sectional side view of an IC package that may includea TFET, in accordance with various embodiments.

FIG. 28 is a cross-sectional side view of an IC device assembly that mayinclude a TFET, in accordance with any of the embodiments disclosedherein.

FIG. 29 is a block diagram of an example computing device that mayinclude a TFET, in accordance with any of the embodiments disclosedherein

DETAILED DESCRIPTION

Disclosed herein are tunneling field effect transistors (TFETs) andrelated methods and computing devices. In some embodiments, a TFET mayinclude: a first source/drain material having a p-type conductivity; asecond source/drain material having an n-type conductivity; a channelmaterial at least partially between the first source/drain material andthe second source/drain material, wherein the channel material has afirst side face and a second side face opposite the first side face; anda gate above the channel material, on the first side face and on thesecond side face.

As noted above, conventional metal oxide semiconductor field effecttransistors (MOSFETs) may transport charge by thermionic emission,thermally inducing the flow of charges over a potential energy barrier.In such MOSFETS, the subthreshold swing may be greater than or equal to60 millivolts/decade of current, limited by the physics of thermionicemission. The subthreshold swing is inversely proportional to theability of the MOSFET to switch quickly between the off state(corresponding to high resistance and low current flow) and the on state(corresponding to low resistance and high current flow), and thus thislower bound on subthreshold swing for conventional MOSFETs represents alimit on the performance achievable by these MOSFETs.

The TFETs disclosed herein may not be limited by thermionic emission asconventional MOSFETs are and may be able to achieve a lower subthresholdswing and thus improved performance. In the TFETs disclosed herein, theprincipal current transport mechanism may be tunneling through apotential energy barrier; at a sufficient gate bias, high current may beachieved by tunneling across the junction between a p-type source and achannel in an n-type TFET (or by tunneling across the junction betweenan n-type source and a channel in a p-type TFET).

Because of their improved subthreshold swing relative to conventionalMOSFETs, some of the TFETs disclosed herein may achieve a higheron-current at a lower supply voltage than conventional MOSFETs. Thus,some of the TFETs disclosed herein may be particularly suitable for lowpower devices, such as mobile computing devices (e.g., smartphones ortablets), wearable computing devices, implantable computing or medicaldevices, etc. For example, in some embodiments, the TFETs disclosedherein may be included in devices having a supply voltage less than 0.5volts.

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, wherein like numeralsdesignate like parts throughout, and in which is shown, by way ofillustration, embodiments that may be practiced. It is to be understoodthat other embodiments may be utilized and structural or logical changesmay be made without departing from the scope of the present disclosure.Therefore, the following detailed description is not to be taken in alimiting sense.

Various operations may be described as multiple discrete actions oroperations in turn, in a manner that is most helpful in understandingthe disclosed subject matter. However, the order of description shouldnot be construed as to imply that these operations are necessarily orderdependent. In particular, these operations may not be performed in theorder of presentation. Operations described may be performed in adifferent order from the described embodiment. Various additionaloperations may be performed, and/or described operations may be omittedin additional embodiments.

For the purposes of the present disclosure, the phrase “A and/or B”means (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B, and C). The term “between,” when usedwith reference to measurement ranges, is inclusive of the ends of themeasurement ranges. As used herein, a “high-k dielectric material” mayrefer to a material having a higher dielectric constant than siliconoxide. As used herein, the term “conductively coupled” refers toelectrical coupling, unless otherwise indicated.

The description uses the phrases “in an embodiment” or “in embodiments,”which may each refer to one or more of the same or differentembodiments. Furthermore, the terms “comprising,” “including,” “having,”and the like, as used with respect to embodiments of the presentdisclosure, are synonymous. The disclosure may use perspective-baseddescriptions such as “above,” “below,” “top,” “bottom,” and “side”; suchdescriptions are used to facilitate the discussion and are not intendedto restrict the application of disclosed embodiments. As used herein, amaterial that “includes” an element may include that element in acompound with one or more other elements; for example, a channel regionthat includes indium may include pure indium, indium arsenide, indiumgallium arsenide, etc.

The accompanying drawings are not necessarily drawn to scale. Althoughmany of the drawings illustrate rectilinear structures with flat wallsand right-angle corners, this is simply for ease of illustration andactual devices made using these techniques will exhibit rounded corners,surface roughness, and other features. For ease of discussion, the term“FIG. 1” may be used to refer to the collection of drawings of FIGS.1A-1E, the term “FIG. 2” may be used to refer to the collection ofdrawings of FIGS. 2A-2D, etc.

FIGS. 1A-1E are various views of a TFET 100, in accordance with someembodiments. FIG. 1A is a side cross-sectional view of the TFET 100along the fin 111, FIG. 1B is a side cross-sectional view taken throughthe section A-A of FIG. 1A (through the gate electrode 118), FIG. 1C isa side view taken toward the first source/drain material region 106, andFIG. 1D is a top view. FIG. 1E, discussed further below, represents thesame view as FIG. 1B, but depicts the non-idealities that commonly arisein device manufacture. Although only a single TFET 100 is depicted inFIG. 1 (and others of the accompanying drawings), this is simply forease of illustration, and an electronic component (e.g., any of thecomponents discussed below with reference to FIGS. 25-29) may includeany number of the TFETs 100 (e.g., in an array or any other desiredarrangement) disclosed herein.

The TFET 100 may include a first source/drain material region 106, asecond source/drain material 107, and a channel material 163 that isdisposed at least partially between the first source/drain materialregion 106 and the second source/drain material 107 to provide a channelfor carriers during operation of the TFET 100. The first source/drainmaterial region 106 and the second source/drain material 107 may haveopposite conductivity types; that is, the first source/drain materialregion 106 may include ample p-type impurities (to increase theconcentration of holes) and the second source/drain material 107 mayinclude ample n-type impurities (to increase the concentration ofelectrons), or the first source/drain material region 106 may includeample n-type impurities and the second source/drain material 107 mayinclude ample p-type impurities. The channel material 163 may have afirst side face 243 and a second, opposing side face 247.

A gate 128 may be disposed above the channel material 163 and may extenddown onto the first side face 243 and the second side face 247. The gate128 may include a gate dielectric 116 and a gate electrode 118. In someembodiments, spacers 130 may be present at the first side 241 of thegate 128 and the second, opposite side 249 of the gate 128.

An insulating material 101 may be disposed on and around thesource/drain materials 106 and 107. The insulating material 101 may bean interlayer dielectric (ILD), such as undoped silicon oxide, dopedsilicon oxide (e.g., borophosphosilicate glass (BPSG) or phosphosilicateglass (PSG)), silicon nitride, silicon oxynitride, or any combination.In some embodiments, an etch stop material 131 (e.g., silicon nitride)may be disposed between the insulating material 101 and the top surfacesof the source/drain materials 106 and 107; in other embodiments, theetch stop material 131 may not be present.

A first source/drain contact 269 may be on the first source/drainmaterial 106, and a second source/drain contact 265 may be on the secondsource/drain material 107. The source/drain contacts 265 and 269 mayinclude any suitable conductive materials, such as tungsten, cobalt, orother contact metals. In some embodiments, the source/drain contacts 265and 269 may include multiple metals; for example, the source/draincontacts 265 and 269 may include a layer of a work function metal or abarrier metal and a fill layer of another metal (e.g., tungsten orcobalt). Additional interconnect structures (not shown), such as theconductive vias and lines discussed below with reference to FIG. 26, maybe in contact with the source/drain contacts 269 and 265 to routeelectrical signals to/from the source/drain contacts 269 and 265.Similarly, additional interconnect structures (not shown) may be incontact with the gate electrode 118 to route electrical signals to/fromthe gate 128.

In the embodiment of FIG. 1, the channel material 163 may be part of afin 111 that also includes a buffer material 161. The fin 111 may beformed on a substrate 102 having a top surface 104; in particular, thebuffer material 161 may be disposed on the top surface 104, and thechannel material 163 may be disposed on the buffer material 161. In someembodiments in which the substrate 102 is crystalline silicon, the topsurface 104 may have a <111> facet (which may improve the growth of thebuffer material 161 and the channel material 163 when these areepitaxially grown on the substrate 102, as discussed below) or a <100>facet.

In some embodiments, the top surface 104 of the substrate 102, thebuffer material 161, the source/drain materials 106 and 107, and thechannel material 163 each have a lattice constant, and the latticeconstants of some or all of these materials may be different.Differences in lattice constant between two adjacent materials mayresult in stress within the materials due to their lattice mismatch. Forexample, when a first material with a smaller lattice constant is grownon a second material with a larger lattice constant, the first materialmay exhibit a tensile strain and the second material may exhibit acompressive strain. If the thickness of a material is less than criticalthickness, the strain can be maintained; if the thickness is greaterthan the critical thickness, the material may start to relax and formdefects. In one embodiment, the channel material 163 and thesource/drain materials 106 and 107 may be uniaxially lattice-stressed ina direction parallel to the length 120 of the gate 128 and may belattice-relaxed in a direction perpendicular to the length 120 of thegate 128.

In some embodiments, the substrate 102 may be a distinct crystallinesubstrate (silicon, germanium, gallium arsenide, sapphire, etc.). Insome embodiments, the substrate 102 may not be a distinct crystallinesubstrate but may instead be a structure that includes one or moreinterconnect layers; such embodiments of the substrate 102 may beappropriate when the TFET 100 will be a back-end device or will beincluded in a package substrate or other assembly.

The buffer material 161 may include one or more epitaxial singlecrystalline semiconductor layers grown atop the substrate 102. In onesuch embodiment, the buffer material 161 may include a material (ormaterials) having a lattice constant different from the substrate 102.The buffer material 161 may serve to grade the lattice constant from thesubstrate 102 to the channel material 163. In some embodiments, thebuffer material 161 may include a group III-V material. In someembodiments, the buffer material 161 may include gallium (e.g., includedin a binary or ternary compound), arsenic (e.g., included in a binary orternary compound), antimony (e.g., included in a binary or ternarycompound), indium, phosphorus, aluminum, aluminum arsenide, aluminumantimonide, gallium arsenide, gallium antimonide, indium phosphide,indium gallium arsenide, aluminum gallium arsenide, indium aluminumarsenide, aluminum arsenic antimonide, aluminum gallium antimonide,indium gallium antimonide, or gallium arsenic antimonide. In someembodiments, the buffer material 161 may include germanium, silicon, orsilicon germanium.

The channel material 163 may include any suitable material for providinga TFET channel. In some embodiments, the channel material may includegallium, indium, arsenic, indium gallium arsenide, or indium arsenide.In some embodiments, the channel material 163 may include silicon orgermanium.

The source/drain materials 106 and 107 may include any suitablematerial. For example, the source/drain materials 106 and 107 mayinclude gallium, antimony, indium, arsenic, nitrogen, phosphorus,gallium antimonide, indium gallium arsenide, indium arsenide,phosphorus, gallium arsenide, indium antimonide, gallium phosphide,indium aluminum arsenide, gallium antimony phosphide, gallium arsenicantimonide, gallium nitride, or indium phosphide. In some embodiments,the source/drain materials 106 and 107 may include silicon, germanium,silicon germanium, or germanium tin.

In some embodiments, the first source/drain material 106 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide) and may include a p-type impurity so as to have a p-typeconductivity; the second source/drain material 107 may include indium,gallium, and arsenic (e.g., in the form of indium gallium arsenide) andmay include an n-type impurity so as to have an n-type conductivity; andthe channel material 163 may include indium, gallium, and arsenic (e.g.,in the form of indium gallium arsenide). In some such embodiments, thebuffer material 161 may include a group III-V material, such as galliumarsenide, and the substrate 102 may be a crystalline silicon substrate.

In some embodiments, the first source/drain material 106 may includegallium and antimony (e.g., in the form of gallium antimonide) and mayinclude a p-type impurity so as to have a p-type conductivity; thesecond source/drain material 107 may include indium and arsenic (e.g.,in the form of indium arsenide) and may include an n-type impurity so asto have an n-type conductivity; and the channel material 163 may includeindium and arsenic (e.g., in the form of indium arsenide). In some suchembodiments, the buffer material 161 may include a group III-V material,such as gallium arsenide, and the substrate 102 may be a crystallinesilicon substrate.

In some embodiments, the first source/drain material 106 may includegallium and antimony (e.g., in the form of gallium antimonide) and mayinclude a p-type impurity so as to have a p-type conductivity; thesecond source/drain material 107 may include indium and arsenic (e.g.,in the form of indium arsenide) and may include an n-type impurity so asto have an n-type conductivity; and the channel material 163 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide). In some such embodiments, the buffer material 161 may includea group III-V material, such as gallium arsenic antimonide, and thesubstrate 102 may be a crystalline silicon substrate.

In some embodiments, the first source/drain material 106 may includeindium and arsenic (e.g., in the form of indium arsenide) and mayinclude a p-type impurity so as to have a p-type conductivity; thesecond source/drain material 107 may include indium and phosphorus(e.g., in the form of indium phosphide) and may include an n-typeimpurity so as to have an n-type conductivity; and the channel material163 may include indium, gallium, and arsenic (e.g., in the form ofindium gallium arsenide). In some such embodiments, the buffer material161 may include a group III-V material, such as gallium arsenide, andthe substrate 102 may be a crystalline silicon substrate.

In some embodiments, the first source/drain material 106, the secondsource/drain material 107, and the channel material 163 may all includea same group III-V material (e.g., indium gallium arsenide). In somesuch embodiments, the substrate 102 may be a crystalline siliconsubstrate.

In some embodiments, the first source/drain material 106, the secondsource/drain material 107, and the channel material 163 may all includesilicon. In some such embodiments, the substrate 102 may be acrystalline silicon substrate.

In some embodiments, the first source/drain material 106, the secondsource/drain material 107, and the channel material 163 may all includegermanium. In some such embodiments, the substrate 102 may be acrystalline silicon substrate.

As noted above, the source/drain materials 106 and 107 may have ann-type conductivity or a p-type conductivity, and the conductivity typesof the first source/drain material 106 may be opposite to theconductivity type of the second source/drain material 107. When asource/drain material includes silicon or germanium, p-type impuritiesmay include boron, aluminum, gallium, or indium, and n-type impuritiesmay include phosphorous, arsenic, or antimony. When a source/drainmaterial includes a group III-V material, p-type impurities may includeberyllium, zinc, magnesium, cadmium or carbon, and n-type impurities mayinclude silicon, germanium, tin, tellurium, sulfur, or selenium. In someembodiments, the source/drain materials 106 and 107 may have a dopingconcentration between 1×10¹⁸ atoms/cm³ to 1×10²¹ atoms/cm³. Thesource/drain materials 106 and 107 may have a uniform dopingconcentration or may include sub-regions of different concentrations ordopant profiles. As discussed in further detail below, in someembodiments, the source/drain materials 106 and 107 may be formed byremoving portions of the fin 111 and then epitaxially growing thesource/drain materials 106 and 107. In other embodiments, thesource/drain materials 106 and 107 may be formed by doping portions ofthe fin 111.

A shallow trench isolation (STI) layer 105 may be present at the base ofthe fin 111, on the substrate 102. The STI layer 105 may serve to reducecurrent leakage between TFETs 100 formed adjacent to one another. TheSTI layer 105 may include any appropriate dielectric material, such assilicon oxide, silicon nitride, silicon oxynitride, a low-k dielectric,and any combination thereof. In some embodiments, the top surface 104 ofthe substrate 102 may be recessed beneath the top surface of the STIlayer 105.

The gate dielectric 116 may include any suitable gate dielectric, suchas, but not limited to, silicon dioxide, silicon oxynitride, and siliconnitride. In some embodiments, the gate dielectric 116 may include ahigh-k gate dielectric layer, such as a metal oxide dielectric (e.g.,tantalum oxide, titanium oxide, hafnium oxide, hafnium silicon oxide,zirconium oxide, etc.). The gate dielectric 116 may also include othertypes of high-k dielectric layers, such as, but not limited to, leadzirconate titanate (PZT) or barium strontium titanate (BST). The gatedielectric 116 may include any combination of the above dielectricmaterials; in some embodiments, the gate dielectric 116 may includemultiple different layers of dielectric materials.

The gate electrode 118 may at least partially surround a portion of thechannel material 163, and the gate dielectric 116 may be disposedbetween the gate electrode 118 and the channel material 163. The gateelectrode 118 may be formed of any suitable conductive material. Forexample, in some embodiments, the gate electrode 118 may include asuperconducting material. In some embodiments, the gate electrode 118may include a metal such as, but not limited to, titanium, titaniumnitride, tantalum, tantalum nitride, tungsten, ruthenium, titaniumaluminum, or any combination thereof. In some embodiments, the gateelectrode 118 may include multiple metal layers. For example, the gateelectrode 118 may include a barrier metal layer proximate to the gatedielectric 116 (e.g., a thin layer of titanium nitride or tantalumnitride), and a bulk metal layer arranged (e.g., nickel or tungsten) sothat the barrier metal layer is between the bulk metal layer and thegate dielectric 116.

The dimensions of the elements in a TFET 100 may take any suitablevalues. In some embodiments, the length 120 of the gate electrode 118may be between 10 nanometers and 100 nanometers (e.g., between 20nanometers and 40 nanometers, or equal to 30 nanometers). In someembodiments, the thickness of the spacers 130 (i.e., in the direction ofthe length 120) may be between 1 nanometer and 10 nanometers (e.g.,between 3 nanometers and 5 nanometers, between 4 nanometers and 6nanometers, or between 4 nanometers and 7 nanometers). In someembodiments, the gate dielectric 116 may have a thickness between 10angstroms and 60 angstroms. In a specific embodiment, the gatedielectric 116 includes hafnium oxide and has a thickness between 1nanometer and 6 nanometers. In some embodiments, the fin 111 may have afin width 258 less than 30 nanometers (e.g., less than 25 nanometers, orless than 10 nanometers). In some embodiments, the fin height 256 may bebetween 3 nanometers and 75 nanometers.

In some embodiments, the length 121 of the first source/drain material106 may be between 25 nanometers and 500 nanometers. In someembodiments, the length 122 of the second source/drain material 107 maytake any of the values discussed above for the length 121; the length122 may be the same as, or different from, the length 121. In someembodiments, the height 124 of the first source/drain material 106 maybe between 10 nanometers and 150 nanometers. In some embodiments, theheight 125 of the second source/drain material 107 may take any of thevalues discussed above for the height 124; the height 124 may be thesame as, or different from, the height 125. In the embodiment of FIG. 1,the height 127 of the portion of the channel material 163 between thefirst source/drain material 106 and the second source/drain material 107may be between 3 nanometers and 75 nanometers.

As noted above, although many of the drawings illustrate rectilinearstructures with flat walls and right-angle corners, this is simply forease of illustration and actual devices made using these techniques willexhibit rounded corners, surface roughness, and other features. Forexample, FIG. 1E is a cross-sectional view of the TFET 100, sharing thesame perspective of FIG. 1B. As illustrated in FIG. 1E, in someembodiments, the fin 111 may have a tapered shape that is wider closerto the substrate 102 and narrower closer to the gate 128. The first sideface 243 of the channel material 163, the top face of the channelmaterial 163, and the second side face 247 of the channel material 163may not be delineated by sharp corners but may instead refer todifferent portions of the surface of the channel material 163. In FIG.1E, the gate dielectric 116 may have more uniform thickness closer tothe top surface of the fin 111 but may be thicker closer to the base ofthe fin 111 (e.g., closer to the substrate 102).

FIGS. 2A-2D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 2A is a side cross-sectional viewof the TFET 100 along the fin 111, FIG. 2B is a side cross-sectionalview taken through the section A-A of FIG. 2A (through the gateelectrode 118), FIG. 2C is a side view taken toward the firstsource/drain material region 106, and FIG. 2D is a top view. The TFET100 of FIG. 2 (and any other suitable TFETs 100 disclosed herein) may bereferred to as a heterojunction TFET when the channel material 163 andthe source material (the first source/drain material 106 or the secondsource/drain material 107, as appropriate) have different materialcompositions, and thus have a band offset. In a heterojunction TFET, thedrain material (the first source/drain material 106 or the secondsource/drain material 107, as appropriate) may or may not have the samematerial composition as the channel material 163. Leakage may be reducedwhen the drain material has a larger band gap than the channel material163.

Like the TFET 100 of FIG. 1, the TFET 100 of FIG. 2 may include a firstsource/drain material region 106, a second source/drain material 107,and a channel material 163 that is disposed at least partially betweenthe first source/drain material region 106 and the second source/drainmaterial 107 to provide a channel for carriers during operation of theTFET 100. The first source/drain material region 106 and the secondsource/drain material 107 may have opposite conductivity types. Thechannel material 163 may have a first side face 243 and a second,opposing side face 247. A gate 128 may be disposed above the channelmaterial 163 and may extend down onto the first side face 243 and thesecond side face 247. FIG. 2 depicts a number of additional elements inthe TFET 100; these elements may take any of the forms discussed above,in any appropriate combination, and discussion of these elements is notrepeated here for ease of illustration.

In the TFET 100 of FIG. 2, the first source/drain material 106 and thesecond source/drain material 107 may extend down to and be in contactwith the buffer material 161, in contrast to the TFET 100 of FIG. 1 inwhich additional portions of the channel material 163 are disposedbetween the buffer material 161 and the source/drain materials 106 and107. As noted above with reference to FIG. 1, although the source/drainmaterials 106 and 107 are shown in FIG. 2 as having equal heights 124and 125, this need not be the case; the heights 124 and 125 may bedifferent, and one or both of the source/drain materials 106 and 107 mayextend into recesses in the buffer material 161.

The TFET 100 of FIG. 2 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 2, the firstsource/drain material 106 may include gallium and antimony (e.g., in theform of gallium antimonide) and may include a p-type impurity so as tohave a p-type conductivity; the second source/drain material 107 mayinclude indium and arsenic (e.g., in the form of indium arsenide) andmay include an n-type impurity so as to have an n-type conductivity; andthe channel material 163 may include indium and arsenic (e.g., in theform of indium arsenide). This embodiment of the TFET 100 may be ann-type TFET 100. In some such embodiments, the buffer material 161 mayinclude a group III-V material, such as gallium arsenide, and thesubstrate 102 may be a crystalline silicon substrate.

In another example of the TFET 100 of FIG. 2, the first source/drainmaterial 106 may include gallium and antimony (e.g., in the form ofgallium antimonide) and may include a p-type impurity so as to have ap-type conductivity; the second source/drain material 107 may includeindium and arsenic (e.g., in the form of indium arsenide) and mayinclude an n-type impurity so as to have an n-type conductivity; and thechannel material 163 may include indium, gallium, and arsenic (e.g., inthe form of indium gallium arsenide). This embodiment of the TFET 100may be an n-type TFET 100. In some such embodiments, the buffer material161 may include a group III-V material, such as gallium arsenicantimonide, and the substrate 102 may be a crystalline siliconsubstrate.

In another example of the TFET 100 of FIG. 2, the first source/drainmaterial 106 may include indium and arsenic (e.g., in the form of indiumarsenide) and may include a p-type impurity so as to have a p-typeconductivity; the second source/drain material 107 may include indiumand phosphorus (e.g., in the form of indium phosphide) and may includean n-type impurity so as to have an n-type conductivity; and the channelmaterial 163 may include indium, gallium, and arsenic (e.g., in the formof indium gallium arsenide). This embodiment of the TFET 100 may be ann-type TFET 100. In some such embodiments, the buffer material 161 mayinclude a group III-V material, such as gallium arsenide, and thesubstrate 102 may be a crystalline silicon substrate.

FIGS. 3A-3D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 3A is a side cross-sectional viewof the TFET 100 along the fin 111, FIG. 3B is a side cross-sectionalview taken through the section A-A of FIG. 3A (through the gateelectrode 118), FIG. 3C is a side view taken toward the firstsource/drain material region 106, and FIG. 3D is a top view.

Like the TFETs 100 of FIGS. 1 and 2, the TFET 100 of FIG. 3 may includea first source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247. A gate 128 may be disposed above thechannel material 163 and may extend down onto the first side face 243and the second side face 247. FIG. 3 depicts a number of additionalelements in the TFET 100; these elements may take any of the formsdiscussed above, in any appropriate combination, and discussion of theseelements is not repeated here for ease of illustration.

The TFET 100 of FIG. 3 may not include a buffer material 161 between thefirst source/drain material 106 and the second source/drain material 107(unlike the embodiments of FIGS. 1 and 2); instead, the channel material163 may be disposed on the substrate 102, and the source/drain materials106 and 107 may be disposed on some of the channel material 163.

The TFET 100 of FIG. 3 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 3, the firstsource/drain material 106, the second source/drain material 107, and thechannel material 163 may all include a same group III-V material (e.g.,indium gallium arsenide). This embodiment of the TFET 100 may be ann-type TFET 100. In some such embodiments, the substrate 102 may be acrystalline silicon substrate.

In other embodiments of the TFET 100 of FIG. 3, the first source/drainmaterial 106, the second source/drain material 107, and the channelmaterial 163 may all include silicon. In some such embodiments, thesubstrate 102 may be a crystalline silicon substrate.

In other embodiments of the TFET 100 of FIG. 3, the first source/drainmaterial 106, the second source/drain material 107, and the channelmaterial 163 may all include germanium. In some such embodiments, thesubstrate 102 may be a crystalline silicon substrate.

FIGS. 4A-4D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 4A is a side cross-sectional viewof the TFET 100 along the fin 111, FIG. 4B is a side cross-sectionalview taken through the section A-A of FIG. 4A (through the gateelectrode 118), FIG. 4C is a side view taken toward the firstsource/drain material region 106, and FIG. 4D is a top view.

Like the TFETs 100 of FIGS. 1-3, the TFET 100 of FIG. 4 may include afirst source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247. A gate 128 may be disposed above thechannel material 163 and may extend down onto the first side face 243and the second side face 247. FIG. 4 depicts a number of additionalelements in the TFET 100; these elements may take any of the formsdiscussed above, in any appropriate combination, and discussion of theseelements is not repeated here for ease of illustration.

The TFET 100 of FIG. 4 may not include a buffer material 161 between thefirst source/drain material 106 and the second source/drain material 107(unlike the embodiments of FIGS. 1 and 2), and unlike the embodiment ofFIG. 3, the source/drain materials 106 and 107 may extend down tocontact the substrate 102. In some embodiments, the source/drainmaterials 106 and 107 may be grown on the substrate 102, as discussedbelow. The channel material 163 may also be disposed on the substrate102.

The TFET 100 of FIG. 4 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 4, the firstsource/drain material 106, the second source/drain material 107, and thechannel material 163 may all include a same group III-V material (e.g.,indium gallium arsenide). In some such embodiments, the substrate 102may be a crystalline silicon substrate.

In other embodiments of the TFET 100 of FIG. 4, the first source/drainmaterial 106, the second source/drain material 107, and the channelmaterial 163 may all include silicon. In some such embodiments, thesubstrate 102 may be a crystalline silicon substrate.

In other embodiments of the TFET 100 of FIG. 4, the first source/drainmaterial 106, the second source/drain material 107, and the channelmaterial 163 may all include germanium. In some such embodiments, thesubstrate 102 may be a crystalline silicon substrate.

FIGS. 5A-5D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 5A is a side cross-sectional viewof the TFET 100 along the nanowire portion 110, FIG. 5B is a sidecross-sectional view taken through the section A-A of FIG. 5A (throughthe gate electrode 118), FIG. 5C is a side view taken toward the firstsource/drain material region 106, and FIG. 5D is a top view.

Like the TFETs 100 of FIGS. 1-4, the TFET 100 of FIG. 4 may include afirst source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247 (as well as top and bottom faces incontact with the gate 128, as discussed below). A gate 128 may bedisposed above the channel material 163 and may extend down onto thefirst side face 243 and the second side face 247. FIG. 5 depicts anumber of additional elements in the TFET 100; these elements may takeany of the forms discussed above, in any appropriate combination, anddiscussion of these elements is not repeated here for ease ofillustration.

In the TFET 100 of FIG. 5, the channel material 163 has a nanowireportion 110 that is surrounded by the gate 128; that is, the gate 128 ison the side faces 243 and 247, as well as the top face and the bottomface of the nanowire portion 110. The TFET 100 of FIG. 5 may thus bereferred to as a “gate-all-around” TFET 100. The first source/drainmaterial 106 may be disposed on a portion of buffer material 161 (whichmay be disposed on the substrate 102), while the second source/drainmaterial 107 may be spaced apart from the buffer material 161 by aportion of the channel material 163. The channel material 163 may thushave an “L-shape” in cross-section, with a height under the gate 128that is greater than a height under the second source/drain material107. The height 124 of the first source/drain material 106 may begreater than the height 125 of the second source/drain material 107, asshown. Although a single nanowire portion 110 is shown in FIG. 5, thechannel material 163 may include multiple nanowire portions 110 arrangedin a vertical array, with the gate 128 wrapped around each of themultiple nanowire portions 110.

In some embodiments, the TFET 100 may include a bottom gate isolationmaterial 114 disposed on the top surface 104 of the substrate 102 andunder the nanowire portion 110. The bottom gate isolation material 114may serve as a capacitive isolation barrier to prevent parasiticcoupling between the top surface 104 and the gate 128. The effectivenessof the bottom gate isolation material 114 as a capacitive isolationbarrier may depend at least in part on its thickness and materialcomposition. In some embodiments, the bottom gate isolation material 114may include any dielectric material, such as silicon oxide, siliconnitride, silicon oxynitride, low-k dielectric materials, etc. In someparticular embodiments, the bottom gate isolation material 114 mayinclude a silicon oxide layer. In some embodiments, the thickness of thebottom gate isolation material 114 may be sufficiently thick so as toisolate the top surface 104 from capacitive coupling by the gate 128. Ina particular embodiment, the thickness of the bottom gate isolationmaterial 114 may be between 5 nanometers and 200 nanometers.

The nanowire portion 110 may run parallel to the top surface 104. Thenanowire portion 110 may have a thickness 133 and a width 132. In someembodiments, the thickness 133 may be between 5 nanometers and 40nanometers (e.g., between 5 nanometers and 10 nanometers, or equal to 10nanometers). In some embodiments, the width 132 may be between 5nanometers and 50 nanometers. In some embodiments, the nanowire portion110 may be ribbon-shaped in that the width 132 is greater than thethickness 133. In some embodiments, the cross-section of the nanowireportion 110 may be circular or oval-shaped rather than rectangular.

The TFET 100 of FIG. 5 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 5, the firstsource/drain material 106 may include indium, gallium, and arsenic(e.g., in the form of indium gallium arsenide) and may include a p-typeimpurity so as to have a p-type conductivity; the second source/drainmaterial 107 may include indium, gallium, and arsenic (e.g., in the formof indium gallium arsenide) and may include an n-type impurity so as tohave an n-type conductivity; and the channel material 163 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide). This embodiment of the TFET 100 may be an n-type TFET 100. Insome such embodiments, the buffer material 161 may include a group III-Vmaterial, such as gallium arsenide, and the substrate 102 may be acrystalline silicon substrate.

Although many of the TFETs 100 illustrated in the accompanying drawingsinclude a fin 111, any of the TFETs 100 disclosed herein may be modifiedso that the channel material 163 includes one or more nanowire portions110 (and thus are all-around-gate TFETs 100).

FIGS. 6A-6D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 6A is a side cross-sectional viewof the TFET 100 along the fin 111, FIG. 6B is a side cross-sectionalview taken through the section A-A of FIG. 6A (through the gateelectrode 118), FIG. 6C is a side view taken toward the firstsource/drain material region 106, and FIG. 6D is a top view.

Like the TFETs 100 of FIGS. 1-5, the TFET 100 of FIG. 6 may include afirst source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247. A gate 128 may be disposed above thechannel material 163, and may extend down onto the first side face 243and the second side face 247. FIG. 6 depicts a number of additionalelements in the TFET 100; these elements may take any of the formsdiscussed above, in any appropriate combination, and discussion of theseelements is not repeated here for ease of illustration.

In the TFET 100 of FIG. 6, an oxide material 167 may be disposed underthe portion of the channel material 163 that is under the gate 128. Theoxide material 167 may separate that portion of the channel material 163from the substrate 102. The first source/drain material 106 may extenddown to and be in contact with the buffer material 161, while the secondsource/drain material 107 may be spaced apart from the buffer material161 by a portion of the channel material 163. Like the TFET 100 of FIG.5, the channel material 163 of the TFET 100 of FIG. 6 may thus have an“L-shape” in cross-section, with a height under the gate 128 that isgreater than a height under the second source/drain material 107. Theheight 124 of the first source/drain material 106 may be greater thanthe height 125 of the second source/drain material 107, as shown.

The TFET 100 of FIG. 6 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 6, the firstsource/drain material 106 may include indium, gallium, and arsenic(e.g., in the form of indium gallium arsenide) and may include a p-typeimpurity so as to have a p-type conductivity; the second source/drainmaterial 107 may include indium, gallium, and arsenic (e.g., in the formof indium gallium arsenide) and may include an n-type impurity so as tohave an n-type conductivity; and the channel material 163 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide). This embodiment of the TFET 100 may be an n-type TFET 100. Insome such embodiments, the buffer material 161 may include a group III-Vmaterial, such as gallium arsenide, and the substrate 102 may be acrystalline silicon substrate.

FIGS. 7A-7D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 7A is a side cross-sectional viewof the TFET 100 along the fin 111, FIG. 7B is a side cross-sectionalview taken through the section A-A of FIG. 7A (through the gateelectrode 118), FIG. 7C is a side view taken toward the firstsource/drain material region 106, and FIG. 7D is a top view.

Like the TFETs 100 of FIGS. 1-6, the TFET 100 of FIG. 7 may include afirst source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247. A gate 128 may be disposed above thechannel material 163 and may extend down onto the first side face 243and the second side face 247. FIG. 7 depicts a number of additionalelements in the TFET 100; these elements may take any of the formsdiscussed above, in any appropriate combination, and discussion of theseelements is not repeated here for ease of illustration.

In the TFET 100 of FIG. 7, the first source/drain material 106 mayextend down to and be in contact with the buffer material 161, while thesecond source/drain material 107 may be spaced apart from the buffermaterial 161 by a portion of the channel material 163. The channelmaterial 163 of the TFET 100 of FIG. 7 may thus have an “L-shape” incross-section, with a height under the gate 128 that is less than aheight under the second source/drain material 107. In some embodiments,the top surface of the second source/drain material 107 may be fartherfrom the substrate 102 than the top surface of the first source/drainmaterial 106; in some such embodiments, the bottom surface of the secondsource/drain material 107 may be farther from the substrate 102 than thetop surface of the first source/drain material 106, as shown. In someembodiments, the height 124 of the first source/drain material 106 maybe greater than the height 125 of the second source/drain material 107,as shown.

The TFET 100 of FIG. 7 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 7, the firstsource/drain material 106 may include indium, gallium, and arsenic(e.g., in the form of indium gallium arsenide) and may include a p-typeimpurity so as to have a p-type conductivity; the second source/drainmaterial 107 may include indium, gallium, and arsenic (e.g., in the formof indium gallium arsenide) and may include an n-type impurity so as tohave an n-type conductivity; and the channel material 163 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide). This embodiment of the TFET 100 may be an n-type TFET 100. Insome such embodiments, the buffer material 161 may include a group III-Vmaterial, such as gallium arsenide, and the substrate 102 may be acrystalline silicon substrate.

FIGS. 8A-8D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 8A is a side cross-sectional viewof the TFET 100 along the fin 111, FIG. 8B is a side cross-sectionalview taken through the section A-A of FIG. 8A (through the gateelectrode 118), FIG. 8C is a side view taken toward the firstsource/drain material region 106, and FIG. 8D is a top view.

Like the TFETs 100 of FIGS. 1-7, the TFET 100 of FIG. 8 may include afirst source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247. A gate 128 may be disposed above thechannel material 163 and may extend down onto the first side face 243and the second side face 247. FIG. 8 depicts a number of additionalelements in the TFET 100; these elements may take any of the formsdiscussed above, in any appropriate combination, and discussion of theseelements is not repeated here for ease of illustration.

In the TFET 100 of FIG. 8, the first source/drain material 106 mayextend down to and be in contact with the buffer material 161, while thesecond source/drain material 107 may be spaced apart from the buffermaterial 161 by a portion of the channel material 163. In someembodiments, the top surface of the second source/drain material 107 maybe farther from the substrate 102 than the top surface of the firstsource/drain material 106, as shown. The height 124 of the firstsource/drain material 106 may be different from, or the same as, theheight 125 of the second source/drain material 107.

The TFET 100 of FIG. 8 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 8, the firstsource/drain material 106 may include indium, gallium, and arsenic(e.g., in the form of indium gallium arsenide) and may include an n-typeimpurity so as to have an n-type conductivity; the second source/drainmaterial 107 may include indium, gallium, and arsenic (e.g., in the formof indium gallium arsenide) and may include a p-type impurity so as tohave a p-type conductivity; and the channel material 163 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide). This embodiment of the TFET 100 may be a p-type TFET 100. Insome such embodiments, the buffer material 161 may include a group III-Vmaterial, such as gallium arsenide, and the substrate 102 may be acrystalline silicon substrate.

FIGS. 9A-9D are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 9A is a side cross-sectional viewof the TFET 100 along the fin 111, FIG. 9B is a side cross-sectionalview taken through the section A-A of FIG. 9A (through the gateelectrode 118), FIG. 9C is a side view taken toward the firstsource/drain material region 106, and FIG. 9D is a top view.

Like the TFETs 100 of FIGS. 1-8, the TFET 100 of FIG. 9 may include afirst source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247. A gate 128 may be disposed above thechannel material 163 and may extend down onto the first side face 243and the second side face 247. FIG. 9 depicts a number of additionalelements in the TFET 100; these elements may take any of the formsdiscussed above, in any appropriate combination, and discussion of theseelements is not repeated here for ease of illustration.

In the TFET 100 of FIG. 9, portions of the channel material 163 aredisposed between the buffer material 161 and the source/drain materials106 and 107 (as in the embodiment of FIG. 1). Unlike the embodiment ofFIG. 1, the height 124 of the first source/drain material 106 and theheight 125 of the second source/drain material 107 may be different(e.g., the height 124 may be greater than the height 125).

The TFET 100 of FIG. 9 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 9, the firstsource/drain material 106 may include indium, gallium, and arsenic(e.g., in the form of indium gallium arsenide) and may include a p-typeimpurity so as to have a p-type conductivity; the second source/drainmaterial 107 may include indium, gallium, and arsenic (e.g., in the formof indium gallium arsenide) and may include an n-type impurity so as tohave an n-type conductivity; and the channel material 163 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide). This embodiment of the TFET 100 may be an n-type TFET 100. Insome such embodiments, the buffer material 161 may include a group III-Vmaterial, such as gallium arsenide, and the substrate 102 may be acrystalline silicon substrate.

FIGS. 10A-10E are various views of another example of a TFET 100, inaccordance with some embodiments. FIG. 10A is a side cross-sectionalview of the TFET 100 along the fin 111, FIG. 10B is a sidecross-sectional view taken through the section A-A of FIG. 10A (throughthe gate electrode 118), FIG. 10C is a side view taken toward the firstsource/drain material region 106, and FIG. 10D is a top view. FIG. 10E,discussed further below, represents the same view as FIG. 10B, butdepicts the non-idealities that commonly arise in device manufacture.

Like the TFETs 100 of FIGS. 1-9, the TFET 100 of FIG. 10 may include afirst source/drain material region 106, a second source/drain material107, and a channel material 163 that is disposed at least partiallybetween the first source/drain material region 106 and the secondsource/drain material 107 to provide a channel for carriers duringoperation of the TFET 100. The first source/drain material region 106and the second source/drain material 107 may have opposite conductivitytypes. The channel material 163 may have a first side face 243 and asecond, opposing side face 247. A gate 128 may be disposed above thechannel material 163 and may extend down onto the first side face 243and the second side face 247. FIG. 10 depicts a number of additionalelements in the TFET 100; these elements may take any of the formsdiscussed above, in any appropriate combination, and discussion of theseelements is not repeated here for ease of illustration.

In the TFET 100 of FIG. 10, the first source/drain material 106 mayextend down to and be in contact with the buffer material 161, while thesecond source/drain material 107 may be spaced apart from the buffermaterial 161 by a portion of the channel material 163. Like the TFET 100of FIG. 5, the channel material 163 of the TFET 100 of FIG. 6 may thushave an “L-shape” in cross-section, with a height under the gate 128that is greater than a height under the second source/drain material107. Additionally, the height 124 of the first source/drain material 106may be greater than the height 125 of the second source/drain material107, as shown, such that the top surface of the first source/drainmaterial 106 is farther from the substrate 102 than the top surface ofthe second source/drain material 107 is from the substrate 102.

The TFET 100 of FIG. 10 may include any of the materials, materialcombinations, and dimensions discussed above with reference to FIG. 1.For example, in some embodiments of the TFET 100 of FIG. 10, the firstsource/drain material 106 may include indium, gallium, and arsenic(e.g., in the form of indium gallium arsenide) and may include a p-typeimpurity so as to have a p-type conductivity; the second source/drainmaterial 107 may include indium, gallium, and arsenic (e.g., in the formof indium gallium arsenide) and may include an n-type impurity so as tohave an n-type conductivity; and the channel material 163 may includeindium, gallium, and arsenic (e.g., in the form of indium galliumarsenide). This embodiment of the TFET 100 may be an n-type TFET 100. Insome such embodiments, the buffer material 161 may include a group III-Vmaterial, such as gallium arsenide, and the substrate 102 may be acrystalline silicon substrate.

As noted above, although many of the drawings illustrate rectilinearstructures with flat walls and right-angle corners, this is simply forease of illustration and actual devices made using these techniques willexhibit rounded corners, surface roughness, and other features. Forexample, FIG. 10E is a cross-sectional view of the TFET 100 of FIG. 10,sharing the same perspective of FIG. 10B. As illustrated in FIG. 10E,the first source/drain material 106 and the second source/drain material107 may have rounded and tapered portions, and elements of the TFET 100that are represented as having a uniform thickness in idealized drawingswill have thicknesses that vary.

The TFETs 100 disclosed herein may be fabricated using any suitabletechniques. For example, FIGS. 11-23 provide various views of assembliesin different stages of the manufacture of the TFET 100 of FIG. 1, inaccordance with various embodiments. Although FIGS. 11-23 depict thefabrication of the TFET 100 of FIG. 1, the manufacturing techniquesrepresented by FIGS. 11-23 may be used to manufacture any of the TFETs100 disclosed herein. Some variations of the techniques of FIGS. 11-23that may be used to form others of the TFETs 100 disclosed herein arediscussed below.

In FIGS. 11-23, the “A” sub-figures represent a cross-sectional viewanalogous to that of FIG. 1A (and FIG. 1E), the “B” sub-figuresrepresent a cross-sectional view analogous to that of FIG. 1B, the “C”sub-figures represent a side view analogous to that of FIG. 1C, and the“D” sub-figures represent a top view analogous to that of FIG. 1D.

FIG. 11 depicts an assembly 300 including a substrate 102 having a fin244 formed therein. The fin 244 may have opposing faces 242 and 246, andan STI layer 105 may be disposed on the faces 242 and 246. The substrate102 and the STI layer 105 may include any of the materials discussedherein. For example, in some embodiments, the substrate 102 may be adistinctly crystalline material, such as crystalline silicon orcrystalline germanium. In some embodiments, the fin 244 may be formedusing conventional photolithography and etching methods. In someembodiments, the STI layer 105 may be formed by first blanket-depositingthe STI layer 105 on the substrate 102 and over the fin 244 usingconventional chemical vapor deposition (CVD) methods to a thicknessgreater than the height of the fin 244. Next, the STI layer 105 may beplanarized using a conventional chemical mechanical planarization (CMP)method.

FIG. 12 illustrates an assembly 302 subsequent to recessing the fin 244of the assembly 300 (FIG. 11) to form a trench 291 whose sidewalls areprovided by the STI layer 105 and whose bottom is provided by theremaining substrate 102. In particular, the bottom of the trench 291 isprovided by the top surface 104 of the substrate 102, as discussedabove. Any suitable etch technique may be used to recess the fin 244.The trench 291 may serve to contain the subsequent growth of the fin111.

FIG. 13 illustrates an assembly 304 subsequent to forming a buffermaterial 161 and a channel material 163 in the trench 291 of theassembly 302 (FIG. 12). The buffer material 161 may be formed on the topsurface 104 of the substrate 102, and the channel material 163 may beformed on the buffer material 161; the buffer material 161 and thechannel material 163 may together provide a fin 111 having side faces.In some embodiments, the buffer material 161 and the channel material163 may be formed by epitaxial growth and may take the form of any ofthe embodiments disclosed herein. To manufacture embodiments of theTFETs 100 that do not include a buffer material 161 (e.g., the TFET 100discussed above with reference to FIG. 3), the formation of the buffermaterial 161 may be omitted. To manufacture embodiments of the TFETs 100that include an oxide material 167 under the channel material 163, thebuffer material 161 may be grown on the top surface 104, a portion ofthe buffer material 161 may be etched away to form a recess, the oxidematerial 167 may be deposited (using any suitable technique) in therecess, and the channel material 163 may be formed on top of the buffermaterial 161/oxide material 167. To manufacture embodiments of the TFETs100 that include nanowire portions 110, the material for the nanowireportions 110 (i.e., the channel material 163) may be grown inalternating layers with a sacrificial material on a bottom gateisolation material 114; prior to forming the sacrificial gate 261 (asdiscussed below with reference to FIGS. 15 and 16), the sacrificialmaterial may be removed, leaving the nanowire portions 110.

The growth of the fin 111 in the trench 291 may geometrically constrainthe fin 111. In some embodiments, the large aspect ratio of the trench291 may reduce the defects in the channel material 163 by aspect ratiotrapping (ART); defects that arise in the deposition of the buffermaterial 161 may propagate diagonally toward, and terminate at, the STIlayer 105 providing the walls of the trench 291 and thus may notcontinue upwards into the channel material 163.

FIG. 14 illustrates an assembly 306 subsequent to recessing the STIlayer 105 of the assembly 304 (FIG. 13) to expose at least some of thefin 111, in particular, to expose the channel material 163. In someembodiments, at least some of the buffer material 161 may be exposedwhen the STI layer 105 is recessed. Any suitable etch technique may beused to recess the STI layer 105.

FIG. 15 illustrates an assembly 308 subsequent to providing asacrificial gate dielectric 262 and a sacrificial gate electrodematerial 264 over the fin 111 of the assembly 306 (FIG. 14). Thesacrificial gate dielectric 262 may be blanket-deposited on top of thefin 111 and on the side faces 243 and 247 of the fin 111. In someembodiments, the sacrificial gate dielectric 262 may be deposited to athickness between 10 angstroms and 50 angstroms. A sacrificial gateelectrode material 264 may then be blanket-deposited on the sacrificialgate dielectric 262 and over the fin 111. The sacrificial gate electrodematerial 264 may be deposited to a thickness that exceeds the height ofthe fin 111, and then may be planarized using conventional CMP methods.

FIG. 16 illustrates an assembly 310 subsequent to providing a hardmask267, patterning the sacrificial gate dielectric 262 and the sacrificialgate electrode material 264 of the assembly 308 (FIG. 15) to form asacrificial gate 261, then providing spacers 130 on the side faces 243and 245 of the sacrificial gate 261. The patterning of the hardmask 267,the sacrificial gate dielectric 262, and the sacrificial gate electrodematerial 264 may expose sacrificial portions 272 of the fin 111.Conventional photolithography and etching methods may be used to performthe patterning. Although a single sacrificial gate 261 is illustrated inFIG. 16, any desired number of sacrificial gates 261 may be patterned onthe fin 111 (e.g., to form multiple TFETs 100 on a single fin 111). Thesacrificial gate 261 may serve to protect the underlying regions of thefin 111 during subsequent removal of sacrificial portions 272 of the fin111, as discussed below.

During the patterning of the sacrificial gate electrode 266, thesacrificial gate dielectric 262 on the sacrificial portions 272 of thefin 111 may be exposed on opposite sides of the sacrificial gateelectrode 266. The sacrificial gate dielectric 262 may serve as an etchstop layer during the patterning and formation of the sacrificial gateelectrode 266, thereby mitigating damage to the fin 111. In a particularembodiment, the sacrificial gate dielectric 262 may be a dielectriclayer (e.g., silicon oxide, silicon nitride, and silicon oxynitride) andthe sacrificial gate electrode material 264 may be a semiconductormaterial (e.g., polycrystalline silicon). After patterning thesacrificial gate electrode material 264, the sacrificial gate dielectric262 may be removed from the top and the side faces 243 and 247 of thesacrificial portions 272 of the fin 111 (e.g., using a conventional wetetch process) to expose the sacrificial portions 272 of the fin 111. Inan embodiment in which the sacrificial gate dielectric 262 is a siliconoxide layer, the sacrificial gate dielectric 262 may be removed using adilute hydrogen fluoride wet etch.

The pair of spacers 130 may be formed using conventional methods offorming selective spacers, as known in the art. In some embodiments, aconformal dielectric spacer layer, such as but not limited to siliconoxide, silicon nitride, silicon oxynitride, and combinations thereof, isfirst blanket-deposited on all structures, including the fin 111. Thedielectric spacer layer may be deposited in a conformal manner so thatit has substantially equal thicknesses on both vertical surfaces (suchas the side faces 243 and 247) and horizontal surfaces. The dielectricspacer layer may be deposited using conventional CVD methods such aslow-pressure chemical vapor deposition (LPCVD) and plasma enhancedchemical vapor deposition (PECVD), for example. In some embodiments, thedielectric spacer layer may be deposited to a thickness between 2nanometers and 10 nanometers. Next, an unpatterned anisotropic etch maybe performed on the dielectric spacer layer using conventionalanisotropic etch methods, such as reactive ion etching (RIE). During theanisotropic etching process, most of the dielectric spacer layer may beremoved from horizontal surfaces, leaving the dielectric spacer layer onthe vertical surfaces, as shown. Next, an unpatterned isotropic etch maybe performed to remove the remaining dielectric spacer layer from anyhorizontal surfaces, leaving pairs of spacers 130. In some embodiments,the isotropic etch is a wet etch process. In a specific embodiment,where the dielectric spacer layer is silicon nitride or silicon oxide,the isotropic etch may employ a wet etchant solution comprisingphosphoric acid or a buffered oxide etch (BOE), respectively. In analternate embodiment, the isotropic etch may be a dry etch process. Inone such embodiment, nitrogen trifluoride gas may be employed in adownstream plasma reactor to isotropically etch the dielectric spacerlayers. Although the spacers 130 are illustrated as having substantiallyrectangular cross-sections, this is for ease of illustration; in someembodiments, the spacers 130 may be thinner farther from the substrate102 and thicker closer to the substrate 102. In some embodiments, thespacers 130 may be curved on their outer faces. In some embodiments, thespacers 130 may extend up onto the sides of the hardmask 267. In someembodiments, the hardmask 267 may not be included.

FIG. 17 illustrates an assembly 312 subsequent to removing thesacrificial portions 272 of the fin 111 of the assembly 310 (FIG. 16) toexpose source/drain regions 274 of the channel material 163. Tomanufacture embodiments of the TFET 100 in which the source/drainmaterials 106 and 107 are formed on the buffer material 161 (e.g., asillustrated in FIG. 2), the sacrificial portions 272 of the fin 111 mayextend all the way down to the buffer material 161. To manufactureembodiments of the TFET 100 in which the source/drain materials 106 and107 are formed on the substrate 102 (e.g., as illustrated in FIG. 4),the sacrificial portions 272 of the fin 111 may extend all the way downto the substrate 102. The sacrificial portions 272 of the fin 244 may beremoved using conventional etching methods, such as wet etching orplasma dry etching. The sacrificial gate 261 may protect the underlyingportions of the fin 111 during this etch.

FIG. 18 illustrates an assembly 314 subsequent to forming portions ofthe second source/drain material 107 on the source/drain regions 274 ofthe assembly 312 (FIG. 17). In some embodiments, the second source/drainmaterial 107 may be formed using conventional epitaxial depositionmethods, such as low-pressure CVD, vapor phase epitaxy, or molecularbeam epitaxy. The second source/drain material 107 may include anyappropriate material, such as any of the materials discussed above.

FIG. 19 illustrates an assembly 316 subsequent to masking off the secondsource/drain material 107 in one of the source/drain regions 274 of theassembly 314 (FIG. 18) with a mask material 271 (while leaving thesecond source/drain material 107 in the other of the source/drainregions 274 exposed), then removing the exposed portion of the secondsource/drain material 107 to leave the associated source/drain region274 exposed again. Any suitable material may be used to mask the secondsource/drain material 107, such as a conformal material. The exposedsecond source/drain material 107 may be removed using conventionaletching methods, such as wet etching or plasma dry etching. Thesacrificial gate 261 may protect the underlying portions of the fin 111during this etch, and the mask material 271 may protect the underlyingportion of the second source/drain material 107.

FIG. 20 illustrates an assembly 318 subsequent to forming a portion ofthe first source/drain material 106 on the exposed source/drain region274 of the assembly 316 (FIG. 19). In some embodiments, the firstsource/drain material 106 may be formed using conventional epitaxialdeposition methods, such as low-pressure CVD, vapor phase epitaxy, ormolecular beam epitaxy. The first source/drain material 106 may includeany appropriate material, such as any of the materials discussed above.In some embodiments in which the first source/drain material 106 and thesecond source drain material 107 are to have different heights (theheights 124 and 125, respectively), the source/drain region 274 may befurther etched prior to growth of the first source/drain material 106 inthe exposed source/drain region 274 to increase the depth of the exposedsource/drain region 274.

In alternative embodiments, the sacrificial portions 272 of the fin 111are not etched away in the manner discussed above with reference to FIG.17. Instead, the first source/drain material 106 and the secondsource/drain material 107 may be formed by selectively doping thesacrificial portions 272 using any suitable techniques (e.g., ionimplantation) to achieve a desired concentration level of p-type andn-type impurities. Additionally, an epitaxial semiconductor film may begrown on the top and sidewalls of the first source/drain material 106and/or the second source/drain material 107 to form raisedsources/drains to decrease current crowding, if desired (not shown).

FIG. 21 illustrates an assembly 320 subsequent to depositing a layer ofetch stop material 131, then depositing and polishing back an insulatingmaterial 101 on the assembly 318 (FIG. 20). The etch stop material 131may include any suitable etch stop material, such as silicon nitride. Insome embodiments, the etch stop material 131 may not be included. Theinsulating material 101 may be an interlayer dielectric (ILD) and may beblanket-deposited over all structures, including the source/drainmaterials 106 and 107 and the sacrificial gate 261, using any suitablemethod (e.g., a CVD method, such as PECVD or LPCVD). A CMP method may beperformed to polish back the blanket-deposited insulating material 101to expose the top of the sacrificial gate 261.

FIG. 22 illustrates an assembly 322 subsequent to removing thesacrificial gate 261 of the assembly 320 (FIG. 21) and forming a gate128 including a conformal gate dielectric 116 and a gate electrode 118.The gate 128, like the sacrificial gate 261, may be disposed on top ofand extend down the side faces of the fin 111. The etch stop material131 and the insulating material 101 may protect the source/drainmaterials 106 and 107 during the removal of the sacrificial gate 261.The sacrificial gate electrode 266 may be removed using any suitableetching method. The gate dielectric 116 may be formed using a highlyconformal deposition process (e.g., atomic layer deposition (ALD)) inorder to ensure the formation of a gate dielectric layer having auniform thickness on the exposed portions of the fin 111. In aparticular embodiment, the gate dielectric 116 may be hafnium oxide andmay be deposited to a thickness between 1 nanometer and 6 nanometers.The gate dielectric 116 may be blanket-deposited and thus may also bepresent on the top surface of the insulating material 101. Next, a gateelectrode material may be blanket-deposited on the gate dielectric 116to form the gate electrode 118. The gate electrode material may bedeposited using any suitable deposition process (e.g., ALD). The blanketgate electrode material and gate dielectric 116 deposited on the top ofthe insulating material 101 may then be chemically mechanicallyplanarized until the top surface of the insulating material 101 isrevealed as shown.

FIG. 23 illustrates an assembly 324 subsequent to removing portions ofthe etch stop material 131 and the insulating material 101 of theassembly 322 (FIG. 22) to form recesses above the source/drain materials106 and 107 and forming source/drain contacts 269 and 265, respectively,in the recesses. Any suitable patterning and deposition techniques maybe used to form the source/drain contacts 265 and 265. For example, afirst conformal layer of a work function metal may be deposited in therecesses, the remainder of the recesses may be filled with another metal(e.g., tungsten or cobalt), and the overburden may be polished back.

FIG. 24 is a flow diagram of an example method 1000 of manufacturing aTFET, in accordance with various embodiments. Although the variousoperations discussed with reference to the method 1000 are shown in aparticular order and once each, the operations may be performed in anysuitable order (e.g., in any combination of parallel or seriesperformance) and may be repeated or omitted as suitable. Additionally,although various operations of the method 1000 may be illustrated withreference to particular embodiments of the TFETs 100 disclosed herein,these are simply examples, and the method 1000 may be used to form anysuitable device.

At 1002, a fin of semiconductor material may be formed. For example, afin 111 including at least a channel material 163 may be formed (e.g.,as discussed above with reference to FIGS. 11-14)

At 1004, a gate may be formed on top and side surfaces of the fin. Thegate may include a first side and an opposing second side along the fin.For example, the sacrificial gate 261 may be formed on the top of thefin 111 and may extend onto the side faces 243 and 247 of the fin. Thesacrificial gate 261 may include opposing sides 241 and 249 along thefin 111. The sacrificial gate 261 may be formed using a replacement gateprocess, as discussed above with reference to FIGS. 15, 16, and 22.

At 1006, a p-type material region may be formed. The p-type materialregion may be proximate to the first side of the gate. For example, thefirst source/drain material 106 may be a p-type material and may beproximate to the side 241 of the sacrificial gate 261.

At 1008, an n-type material region may be formed. The n-type materialregion may be proximate to the second side of the gate. For example, thesecond source/drain material 107 may be an n-type material and may beproximate to the side 249 of the sacrificial gate 261.

The TFETs 100 disclosed herein may be included in any suitableelectronic component. FIGS. 25-29 illustrate various examples ofapparatuses that may include any of the TFETs 100 disclosed herein.

FIG. 25 is a top view of a wafer 1500 and dies 1502 that may include oneor more TFETs 100, or may be included in an IC package whose substrateincludes one or more TFETs 100 (e.g., as discussed below with referenceto FIG. 11) in accordance with any of the embodiments disclosed herein.The wafer 1500 may be composed of semiconductor material and may includeone or more dies 1502 having IC structures formed on a surface of thewafer 1500. Each of the dies 1502 may be a repeating unit of asemiconductor product that includes any suitable IC. After thefabrication of the semiconductor product is complete, the wafer 1500 mayundergo a singulation process in which each of the dies 1502 isseparated from one another to provide discrete “chips” of thesemiconductor product. The die 1502 may include one or more TFETs 100(e.g., as discussed below with reference to FIG. 10), one or more othertypes of transistors (e.g., some of the transistors 1640 of FIG. 10,discussed below) and/or supporting circuitry to route electrical signalsto the transistors, as well as any other IC components. In someembodiments, the wafer 1500 or the die 1502 may include a memory device(e.g., a random access memory (RAM) device, such as a static RAM (SRAM)device, a magnetic RAM (MRAM) device, a resistive RAM (RRAM) device, aconductive-bridging RAM (CBRAM) device, etc.), a logic device (e.g., anAND, OR, NAND, or NOR gate), or any other suitable circuit element.Multiple ones of these devices may be combined on a single die 1502. Forexample, a memory array formed by multiple memory devices may be formedon a same die 1502 as a processing device (e.g., the processing device1802 of FIG. 29) or other logic that is configured to store informationin the memory devices or execute instructions stored in the memoryarray.

FIG. 26 is a cross-sectional side view of an IC device 1600 that mayinclude one or more TFETs 100, or may be included in an IC package whosesubstrate includes one or more TFETs 100 (e.g., as discussed below withreference to FIG. 27), in accordance with any of the embodimentsdisclosed herein. One or more of the IC devices 1600 may be included inone or more dies 1502 (FIG. 25). The IC device 1600 may be formed on asubstrate 1602 (e.g., the wafer 1500 of FIG. 25) and may be included ina die (e.g., the die 1502 of FIG. 25). The substrate 1602 may be asemiconductor substrate composed of semiconductor material systemsincluding, for example, n-type or p-type materials systems (or acombination of both). The substrate 1602 may include, for example, acrystalline substrate formed using a bulk silicon or asilicon-on-insulator (SOI) substructure. In some embodiments, thesubstrate 1602 may be formed using alternative materials, which may ormay not be combined with silicon, that include but are not limited togermanium, indium antimonide, lead telluride, indium arsenide, indiumphosphide, gallium arsenide, or gallium antimonide. Further materialsclassified as group II-VI, III-V, or IV may also be used to form thesubstrate 1602. Although a few examples of materials from which thesubstrate 1602 may be formed are described here, any material that mayserve as a foundation for an IC device 1600 may be used. The substrate1602 may be part of a singulated die (e.g., the dies 1502 of FIG. 25) ora wafer (e.g., the wafer 1500 of FIG. 25).

The IC device 1600 may include one or more device layers 1604 disposedon the substrate 1602. The device layer 1604 may include features of oneor more transistors 1640 (e.g., MOSFETs) formed on the substrate 1602.The device layer 1604 may include, for example, one or more sourceand/or drain (S/D) regions 1620, a gate 1622 to control current flow inthe transistors 1640 between the S/D regions 1620, and one or more S/Dcontacts 1624 to route electrical signals to/from the S/D regions 1620.The transistors 1640 may include additional features not depicted forthe sake of clarity, such as device isolation regions, gate contacts,and the like. The transistors 1640 are not limited to the type andconfiguration depicted in FIG. 26 and may include a wide variety ofother types and configurations such as, for example, planar transistors,non-planar transistors, or a combination of both. Non-planar transistorsmay include FinFET transistors, such as double-gate transistors ortri-gate transistors, and wrap-around or all-around gate transistors,such as nanoribbon and nanowire transistors.

Each transistor 1640 may include a gate 1622 formed of at least twolayers, a gate dielectric layer and a gate electrode layer. The gatedielectric layer may include one layer or a stack of layers. The one ormore layers may include silicon oxide, silicon dioxide, silicon carbide,and/or a high-k dielectric material. The high-k dielectric material mayinclude elements such as hafnium, silicon, oxygen, titanium, tantalum,lanthanum, aluminum, zirconium, barium, strontium, yttrium, lead,scandium, niobium, and zinc. Examples of high-k materials that may beused in the gate dielectric layer include, but are not limited to,hafnium oxide, hafnium silicon oxide, lanthanum oxide, lanthanumaluminum oxide, zirconium oxide, zirconium silicon oxide, tantalumoxide, titanium oxide, barium strontium titanium oxide, barium titaniumoxide, strontium titanium oxide, yttrium oxide, aluminum oxide, leadscandium tantalum oxide, and lead zinc niobate. In some embodiments, anannealing process may be carried out on the gate dielectric layer toimprove its quality when a high-k material is used.

The gate electrode layer may be formed on the gate dielectric layer andmay include at least one p-type work function metal or n-type workfunction metal, depending on whether the transistor 1640 is to be ap-type metal oxide semiconductor (PMOS) or an n-type metal oxidesemiconductor (NMOS) transistor. In some implementations, the gateelectrode layer may consist of a stack of two or more metal layers,where one or more metal layers are work function metal layers and atleast one metal layer is a fill metal layer. Further metal layers may beincluded for other purposes, such as a barrier layer. For a PMOStransistor, metals that may be used for the gate electrode include, butare not limited to, ruthenium, palladium, platinum, cobalt, nickel, andconductive metal oxides (e.g., ruthenium oxide), and any of the metalsdiscussed below with reference to an NMOS transistor (e.g., for workfunction tuning). For an NMOS transistor, metals that may be used forthe gate electrode include, but are not limited to, hafnium, zirconium,titanium, tantalum, aluminum, alloys of these metals, and carbides ofthese metals (e.g., hafnium carbide, zirconium carbide, titaniumcarbide, tantalum carbide, and aluminum carbide), and any of the metalsdiscussed above with reference to a PMOS transistor (e.g., for workfunction tuning).

In some embodiments, when viewed as a cross-section of the transistor1640 along the source-channel-drain direction, the gate electrode mayconsist of a U-shaped structure that includes a bottom portionsubstantially parallel to the surface of the substrate and two sidewallportions that are substantially perpendicular to the top surface of thesubstrate. In other embodiments, at least one of the metal layers thatform the gate electrode may simply be a planar layer that issubstantially parallel to the top surface of the substrate and does notinclude sidewall portions substantially perpendicular to the top surfaceof the substrate. In other embodiments, the gate electrode may consistof a combination of U-shaped structures and planar, non-U-shapedstructures. For example, the gate electrode may consist of one or moreU-shaped metal layers formed atop one or more planar, non-U-shapedlayers.

In some embodiments, a pair of sidewall spacers may be formed onopposing sides of the gate stack to bracket the gate stack. The sidewallspacers may be formed from a material such as silicon nitride, siliconoxide, silicon carbide, silicon nitride doped with carbon, and siliconoxynitride. Processes for forming sidewall spacers are well known in theart and generally include deposition and etching process steps. In someembodiments, a plurality of spacer pairs may be used; for instance, twopairs, three pairs, or four pairs of sidewall spacers may be formed onopposing sides of the gate stack.

The S/D regions 1620 may be formed within the substrate 1602 adjacent tothe gate 1622 of each transistor 1640. The S/D regions 1620 may beformed using either an implantation/diffusion process or anetching/deposition process, for example. In the former process, dopantssuch as boron, aluminum, antimony, phosphorous, or arsenic may beion-implanted into the substrate 1602 to form the S/D regions 1620. Anannealing process that activates the dopants and causes them to diffusefarther into the substrate 1602 may follow the ion implantation process.In the latter process, the substrate 1602 may first be etched to formrecesses at the locations of the S/D regions 1620. An epitaxialdeposition process may then be carried out to fill the recesses withmaterial that is used to fabricate the S/D regions 1620. In someimplementations, the S/D regions 1620 may be fabricated using a siliconalloy such as silicon germanium or silicon carbide. In some embodiments,the epitaxially deposited silicon alloy may be doped in situ withdopants such as boron, arsenic, or phosphorous. In some embodiments, theS/D regions 1620 may be formed using one or more alternate semiconductormaterials such as germanium or a group III-V material or alloy. Infurther embodiments, one or more layers of metal and/or metal alloys maybe used to form the S/D regions 1620.

In some embodiments, the device layer 1604 may include one or more TFETs100, in addition to or instead of the transistors 1640. FIG. 26illustrates a single TFET 100 in the device layer 1604 for illustrationpurposes, but any number and structure of TFETs 100 may be included in adevice layer 1604. A TFET 100 included in a device layer 1604 may bereferred to as a “front end” device. In some embodiments, the IC device1600 may not include any front end TFETs 100. One or more TFETs 100 inthe device layer 1604 may be coupled to any suitable other ones of thedevices in the device layer 1604, to any devices in the metallizationstack 1619 (discussed below), and/or to one or more of the conductivecontacts 1636 (discussed below).

Electrical signals, such as power and/or input/output (I/O) signals, maybe routed to and/or from the devices (e.g., transistors 1640 and/orTFETs 100) of the device layer 1604 through one or more interconnectlayers disposed on the device layer 1604 (illustrated in FIG. 26 asinterconnect layers 1606-1610). For example, electrically conductivefeatures of the device layer 1604 (e.g., the gate 1622 and the S/Dcontacts 1624) may be electrically coupled with the interconnectstructures 1628 of the interconnect layers 1606-1610. The one or moreinterconnect layers 1606-1610 may form a metallization stack (alsoreferred to as an “ILD stack”) 1619 of the IC device 1600. In someembodiments, one or more TFETs 100 may be disposed in one or more of theinterconnect layers 1606-1610, in accordance with any of the techniquesdisclosed herein. FIG. 26 illustrates a single TFET 100 in theinterconnect layer 1608 for illustration purposes, but any number andstructure of TFETs 100 may be included in any one or more of the layersin a metallization stack 1619. A TFET 100 included in the metallizationstack 1619 may be referred to as a “back-end” device. In someembodiments, the IC device 1600 may not include any back-end TFETs 100;in some embodiments, the IC device 1600 may include both front- andback-end TFETs 100. One or more TFETs 100 in the metallization stack1619 may be coupled to any suitable ones of the devices in the devicelayer 1604 and/or to one or more of the conductive contacts 1636(discussed below).

The interconnect structures 1628 may be arranged within the interconnectlayers 1606-1610 to route electrical signals according to a wide varietyof designs (in particular, the arrangement is not limited to theparticular configuration of interconnect structures 1628 depicted inFIG. 26). Although a particular number of interconnect layers 1606-1610is depicted in FIG. 26, embodiments of the present disclosure include ICdevices having more or fewer interconnect layers than depicted.

In some embodiments, the interconnect structures 1628 may include lines1628 a and/or vias 1628 b filled with an electrically conductivematerial such as a metal. The lines 1628 a may be arranged to routeelectrical signals in a direction of a plane that is substantiallyparallel with a surface of the substrate 1602 upon which the devicelayer 1604 is formed. For example, the lines 1628 a may route electricalsignals in a direction in and out of the page from the perspective ofFIG. 26. The vias 1628 b may be arranged to route electrical signals ina direction of a plane that is substantially perpendicular to thesurface of the substrate 1602 upon which the device layer 1604 isformed. In some embodiments, the vias 1628 b may electrically couplelines 1628 a of different interconnect layers 1606-1610 together.

The interconnect layers 1606-1610 may include a dielectric material 1626disposed between the interconnect structures 1628, as shown in FIG. 26.In some embodiments, the dielectric material 1626 disposed between theinterconnect structures 1628 in different ones of the interconnectlayers 1606-1610 may have different compositions; in other embodiments,the composition of the dielectric material 1626 between differentinterconnect layers 1606-1610 may be the same.

A first interconnect layer 1606 (referred to as Metal 1 or “M1”) may beformed directly on the device layer 1604. In some embodiments, the firstinterconnect layer 1606 may include lines 1628 a and/or vias 1628 b, asshown. The lines 1628 a of the first interconnect layer 1606 may becoupled with contacts (e.g., the S/D contacts 1624) of the device layer1604.

A second interconnect layer 1608 (referred to as Metal 2 or “M2”) may beformed directly on the first interconnect layer 1606. In someembodiments, the second interconnect layer 1608 may include vias 1628 bto couple the lines 1628 a of the second interconnect layer 1608 withthe lines 1628 a of the first interconnect layer 1606. Although thelines 1628 a and the vias 1628 b are structurally delineated with a linewithin each interconnect layer (e.g., within the second interconnectlayer 1608) for the sake of clarity, the lines 1628 a and the vias 1628b may be structurally and/or materially contiguous (e.g., simultaneouslyfilled during a dual-damascene process) in some embodiments.

A third interconnect layer 1610 (referred to as Metal 3 or “M3”) (andadditional interconnect layers, as desired) may be formed in successionon the second interconnect layer 1608 according to similar techniquesand configurations described in connection with the second interconnectlayer 1608 or the first interconnect layer 1606. In some embodiments,the interconnect layers that are “higher up” in the metallization stack1619 in the IC device 1600 (i.e., further away from the device layer1604) may be thicker.

The IC device 1600 may include a solder resist material 1634 (e.g.,polyimide or similar material) and one or more conductive contacts 1636formed on the interconnect layers 1606-1610. In FIG. 26, the conductivecontacts 1636 are illustrated as taking the form of bond pads. Theconductive contacts 1636 may be electrically coupled with theinterconnect structures 1628 and configured to route the electricalsignals of the transistor(s) 1640 to other external devices. Forexample, solder bonds may be formed on the one or more conductivecontacts 1636 to mechanically and/or electrically couple a chipincluding the IC device 1600 with another component (e.g., a circuitboard). The IC device 1600 may include additional or alternatestructures to route the electrical signals from the interconnect layers1606-1610; for example, the conductive contacts 1636 may include otheranalogous features (e.g., posts) that route the electrical signals toexternal components.

FIG. 27 is a cross-sectional view of an example IC package 1650 that mayinclude one or more TFETs 100. The package substrate 1652 may be formedof a dielectric material and may have conductive pathways extendingthrough the dielectric material between the face 1672 and the face 1674,or between different locations on the 1672 and/or between differentlocations on the face 1674. These conductive pathways may take the formof any of the interconnect structures 1628 discussed above withreference to FIG. 26. In some embodiments, the package substrate 1652may include one or more TFETs 100 (not shown) in accordance with any ofthe embodiments disclosed herein. In some embodiments, no TFETs 100 maybe included in the package substrate 1652.

The IC package 1650 may include a die 1656 coupled to the packagesubstrate 1652 via conductive contacts 1654 of the die 1656, first-levelinterconnects 1658, and conductive contacts 1660 of the packagesubstrate 1652. The conductive contacts 1660 may be coupled toconductive pathways 1662 through the package substrate 1652, allowingcircuitry within the die 1656 to electrically couple to various ones ofthe conductive contacts 1664 (or to other devices included in thepackage substrate 1652, such as TFETs 100, not shown). The first-levelinterconnects 1658 illustrated in FIG. 27 are solder bumps, but anysuitable first-level interconnects 1658 may be used. As used herein, a“conductive contact” may refer to a portion of conductive material(e.g., metal) serving as an electrical interface between differentcomponents; conductive contacts may be recessed in, flush with, orextending away from a surface of a component and may take any suitableform (e.g., a conductive pad or socket).

In some embodiments, an underfill material 1666 may be disposed betweenthe die 1656 and the package substrate 1652 around the first-levelinterconnects 1658, and a mold compound 1668 may be disposed around thedie 1656 and in contact with the package substrate 1652. In someembodiments, the underfill material 1666 may be the same as the moldcompound 1668. Example materials that may be used for the underfillmaterial 1666 and the mold compound 1668 are epoxy mold materials, assuitable. Second-level interconnects 1670 may be coupled to theconductive contacts 1664. The second-level interconnects 1670illustrated in FIG. 27 are solder balls (e.g., for a ball grid arrayarrangement), but any suitable second-level interconnects 16770 may beused (e.g., pins in a pin grid array arrangement or lands in a land gridarray arrangement). The second-level interconnects 1670 may be used tocouple the IC package 1650 to another component, such as a circuit board(e.g., a motherboard), an interposer, or another IC package, as known inthe art and as discussed below with reference to FIG. 28.

In FIG. 27, the IC package 1650 is a flip chip package. The die 1656 maytake the form of any of the embodiments of the die 1502 discussed herein(e.g., may include any of the embodiments of the IC device 1600). Insome embodiments, the die 1656 may include one or more TFETs 100 (e.g.,as discussed above with reference to FIG. 25 and FIG. 26); in otherembodiments, the die 1656 may not include any TFETs 100.

Although the IC package 1650 illustrated in FIG. 27 is a flip chippackage, other package architectures may be used. For example, the ICpackage 1650 may be a ball grid array (BGA) package, such as an embeddedwafer-level ball grid array (eWLB) package. In another example, the ICpackage 1650 may be a wafer-level chip scale package (WLCSP) or a panelfanout (FO) package. Although a single die 1656 is illustrated in the ICpackage 1650 of FIG. 27, an IC package 1650 may include multiple dies1656. An IC package 1650 may include additional passive components, suchas surface-mount resistors, capacitors, and inductors disposed on thefirst face 1672 or the second face 1674 of the package substrate 1652.More generally, an IC package 1650 may include any other active orpassive components known in the art.

FIG. 28 is a cross-sectional side view of an IC device assembly 1700that may include one or more IC packages or other electronic components(e.g., a die) including one or more TFETs 100, in accordance with any ofthe embodiments disclosed herein. The IC device assembly 1700 includes anumber of components disposed on a circuit board 1702 (which may be, forexample, a motherboard). The IC device assembly 1700 includes componentsdisposed on a first face 1740 of the circuit board 1702 and an opposingsecond face 1742 of the circuit board 1702; generally, components may bedisposed on one or both faces 1740 and 1742. Any of the IC packagesdiscussed below with reference to the IC device assembly 1700 may takethe form of any of the embodiments of the IC package 1650 discussedabove with reference to FIG. 27 (e.g., may include one or more TFETs 100in a package substrate 1652 or in a die).

In some embodiments, the circuit board 1702 may be a printed circuitboard (PCB) including multiple metal layers separated from one anotherby layers of dielectric material and interconnected by electricallyconductive vias. Any one or more of the metal layers may be formed in adesired circuit pattern to route electrical signals (optionally inconjunction with other metal layers) between the components coupled tothe circuit board 1702. In other embodiments, the circuit board 1702 maybe a non-PCB substrate.

The IC device assembly 1700 illustrated in FIG. 28 includes apackage-on-interposer structure 1736 coupled to the first face 1740 ofthe circuit board 1702 by coupling components 1716. The couplingcomponents 1716 may electrically and mechanically couple thepackage-on-interposer structure 1736 to the circuit board 1702, and mayinclude solder balls (as shown in FIG. 28), male and female portions ofa socket, an adhesive, an underfill material, and/or any other suitableelectrical and/or mechanical coupling structure.

The package-on-interposer structure 1736 may include an IC package 1720coupled to an interposer 1704 by coupling components 1718. The couplingcomponents 1718 may take any suitable form for the application, such asthe forms discussed above with reference to the coupling components1716. Although a single IC package 1720 is shown in FIG. 28, multiple ICpackages may be coupled to the interposer 1704; indeed, additionalinterposers may be coupled to the interposer 1704. The interposer 1704may provide an intervening substrate used to bridge the circuit board1702 and the IC package 1720. The IC package 1720 may be or include, forexample, a die (the die 1502 of FIG. 25), an IC device (e.g., the ICdevice 1600 of FIG. 26), or any other suitable component. Generally, theinterposer 1704 may spread a connection to a wider pitch or reroute aconnection to a different connection. For example, the interposer 1704may couple the IC package 1720 (e.g., a die) to a set of BGA conductivecontacts of the coupling components 1716 for coupling to the circuitboard 1702. In the embodiment illustrated in FIG. 28, the IC package1720 and the circuit board 1702 are attached to opposing sides of theinterposer 1704; in other embodiments, the IC package 1720 and thecircuit board 1702 may be attached to a same side of the interposer1704. In some embodiments, three or more components may beinterconnected by way of the interposer 1704.

The interposer 1704 may be formed of an epoxy resin, afiberglass-reinforced epoxy resin, an epoxy resin with inorganicfillers, a ceramic material, or a polymer material such as polyimide. Insome embodiments, the interposer 1704 may be formed of alternate rigidor flexible materials that may include the same materials describedabove for use in a semiconductor substrate, such as silicon, germanium,and other group III-V and group IV materials. The interposer 1704 mayinclude metal interconnects 1708 and vias 1710, including but notlimited to through-silicon vias (TSVs) 1706. The interposer 1704 mayfurther include embedded devices 1714, including both passive and activedevices. Such devices may include, but are not limited to, capacitors,decoupling capacitors, resistors, inductors, fuses, diodes,transformers, sensors, electrostatic discharge (ESD) devices, and memorydevices. More complex devices such as radio frequency devices, poweramplifiers, power management devices, antennas, arrays, sensors, andmicroelectromechanical systems (MEMS) devices may also be formed on theinterposer 1704. The package-on-interposer structure 1736 may take theform of any of the package-on-interposer structures known in the art. Insome embodiments, the interposer 1704 may include one or more TFETs 100(not shown).

The IC device assembly 1700 may include an IC package 1724 coupled tothe first face 1740 of the circuit board 1702 by coupling components1722. The coupling components 1722 may take the form of any of theembodiments discussed above with reference to the coupling components1716, and the IC package 1724 may take the form of any of theembodiments discussed above with reference to the IC package 1720.

The IC device assembly 1700 illustrated in FIG. 28 includes apackage-on-package structure 1734 coupled to the second face 1742 of thecircuit board 1702 by coupling components 1728. The package-on-packagestructure 1734 may include an IC package 1726 and an IC package 1732coupled together by coupling components 1730 such that the IC package1726 is disposed between the circuit board 1702 and the IC package 1732.The coupling components 1728 and 1730 may take the form of any of theembodiments of the coupling components 1716 discussed above, and the ICpackages 1726 and 1732 may take the form of any of the embodiments ofthe IC package 1720 discussed above. The package-on-package structure1734 may be configured in accordance with any of the package-on-packagestructures known in the art.

FIG. 29 is a block diagram of an example electrical device 1800 that mayinclude one or more TFETs 100, in accordance with any of the embodimentsdisclosed herein. For example, any suitable ones of the components ofthe electrical device 1800 may include one or more of the IC packages1650, IC devices 1600, or dies 1502 disclosed herein. A number ofcomponents are illustrated in FIG. 29 as included in the electricaldevice 1800, but any one or more of these components may be omitted orduplicated, as suitable for the application. In some embodiments, someor all of the components included in the electrical device 1800 may beattached to one or more motherboards. In some embodiments, some or allof these components are fabricated onto a single system-on-a-chip (SoC)die.

Additionally, in various embodiments, the electrical device 1800 may notinclude one or more of the components illustrated in FIG. 29, but theelectrical device 1800 may include interface circuitry for coupling tothe one or more components. For example, the electrical device 1800 maynot include a display device 1806 but may include display deviceinterface circuitry (e.g., a connector and driver circuitry) to which adisplay device 1806 may be coupled. In another set of examples, theelectrical device 1800 may not include an audio input device 1824 or anaudio output device 1808, but may include audio input or output deviceinterface circuitry (e.g., connectors and supporting circuitry) to whichan audio input device 1824 or audio output device 1808 may be coupled.

The electrical device 1800 may include a processing device 1802 (e.g.,one or more processing devices). As used herein, the term “processingdevice” or “processor” may refer to any device or portion of a devicethat processes electronic data from registers and/or memory to transformthat electronic data into other electronic data that may be stored inregisters and/or memory. The processing device 1802 may include one ormore digital signal processors (DSPs), application-specific integratedcircuits (ASICs), central processing units (CPUs), graphics processingunits (GPUs), cryptoprocessors (specialized processors that executecryptographic algorithms within hardware), server processors, or anyother suitable processing devices. The electrical device 1800 mayinclude a memory 1804, which may itself include one or more memorydevices such as volatile memory (e.g., dynamic random access memory(DRAM)), nonvolatile memory (e.g., read-only memory (ROM)), flashmemory, solid state memory, and/or a hard drive. In some embodiments,the memory 1804 may include memory that shares a die with the processingdevice 1802. This memory may be used as cache memory and may includeembedded dynamic random access memory (eDRAM) or spin transfer torquemagnetic random access memory (STT-MRAM).

In some embodiments, the electrical device 1800 may include acommunication chip 1812 (e.g., one or more communication chips). Forexample, the communication chip 1812 may be configured for managingwireless communications for the transfer of data to and from theelectrical device 1800. The term “wireless” and its derivatives may beused to describe circuits, devices, systems, methods, techniques,communications channels, etc., that may communicate data through the useof modulated electromagnetic radiation through a nonsolid medium. Theterm does not imply that the associated devices do not contain anywires, although in some embodiments they might not.

The communication chip 1812 may implement any of a number of wirelessstandards or protocols, including but not limited to Institute forElectrical and Electronic Engineers (IEEE) standards including Wi-Fi(IEEE 802.11 family), IEEE 802.16 standards (e.g., IEEE 802.16-2005Amendment), Long-Term Evolution (LTE) project along with any amendments,updates, and/or revisions (e.g., advanced LTE project, ultra mobilebroadband (UMB) project (also referred to as “3GPP2”), etc.). IEEE802.16 compatible Broadband Wireless Access (BWA) networks are generallyreferred to as WiMAX networks, an acronym that stands for WorldwideInteroperability for Microwave Access, which is a certification mark forproducts that pass conformity and interoperability tests for the IEEE802.16 standards. The communication chip 1812 may operate in accordancewith a Global System for Mobile Communication (GSM), General PacketRadio Service (GPRS), Universal Mobile Telecommunications System (UMTS),High Speed Packet Access (HSPA), Evolved HSPA (E-HSPA), or LTE network.The communication chip 1812 may operate in accordance with Enhanced Datafor GSM Evolution (EDGE), GSM EDGE Radio Access Network (GERAN),Universal Terrestrial Radio Access Network (UTRAN), or Evolved UTRAN(E-UTRAN). The communication chip 1812 may operate in accordance withCode Division Multiple Access (CDMA), Time Division Multiple Access(TDMA), Digital Enhanced Cordless Telecommunications (DECT),Evolution-Data Optimized (EV-DO), and derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The communication chip 1812 may operate in accordance with otherwireless protocols in other embodiments. The electrical device 1800 mayinclude an antenna 1822 to facilitate wireless communications and/or toreceive other wireless communications (such as AM or FM radiotransmissions).

In some embodiments, the communication chip 1812 may manage wiredcommunications, such as electrical, optical, or any other suitablecommunication protocols (e.g., the Ethernet). As noted above, thecommunication chip 1812 may include multiple communication chips. Forinstance, a first communication chip 1812 may be dedicated toshorter-range wireless communications such as Wi-Fi or Bluetooth, and asecond communication chip 1812 may be dedicated to longer-range wirelesscommunications such as global positioning system (GPS), EDGE, GPRS,CDMA, WiMAX, LTE, EV-DO, or others. In some embodiments, a firstcommunication chip 1812 may be dedicated to wireless communications, anda second communication chip 1812 may be dedicated to wiredcommunications.

The electrical device 1800 may include battery/power circuitry 1814. Thebattery/power circuitry 1814 may include one or more energy storagedevices (e.g., batteries or capacitors) and/or circuitry for couplingcomponents of the electrical device 1800 to an energy source separatefrom the electrical device 1800 (e.g., AC line power). As noted above,in some embodiments, the electrical device 1800 may be a low powerdevice (e.g., may have a power supply that proves a supply voltage lessthan 1 volt, or less than 0.5 volts).

The electrical device 1800 may include a display device 1806 (orcorresponding interface circuitry, as discussed above). The displaydevice 1806 may include any visual indicators, such as a heads-updisplay, a computer monitor, a projector, a touchscreen display, aliquid crystal display (LCD), a light-emitting diode display, or a flatpanel display.

The electrical device 1800 may include an audio output device 1808 (orcorresponding interface circuitry, as discussed above). The audio outputdevice 1808 may include any device that generates an audible indicator,such as speakers, headsets, or earbuds, for example.

The electrical device 1800 may include an audio input device 1824 (orcorresponding interface circuitry, as discussed above). The audio inputdevice 1824 may include any device that generates a signalrepresentative of a sound, such as microphones, microphone arrays, ordigital instruments (e.g., instruments having a musical instrumentdigital interface (MIDI) output).

The electrical device 1800 may include a GPS device 1818 (orcorresponding interface circuitry, as discussed above). The GPS device1818 may be in communication with a satellite-based system and mayreceive a location of the electrical device 1800, as known in the art.

The electrical device 1800 may include an other output device 1810 (orcorresponding interface circuitry, as discussed above). Examples of theother output device 1810 may include an audio codec, a video codec, aprinter, a wired or wireless transmitter for providing information toother devices, or an additional storage device.

The electrical device 1800 may include an other input device 1820 (orcorresponding interface circuitry, as discussed above). Examples of theother input device 1820 may include an accelerometer, a gyroscope, acompass, an image capture device, a keyboard, a cursor control devicesuch as a mouse, a stylus, a touchpad, a bar code reader, a QuickResponse (QR) code reader, any sensor, or a radio frequencyidentification (RFID) reader.

The electrical device 1800 may have any desired form factor, such as ahand-held or mobile electrical device (e.g., a cell phone, a smartphone, a mobile internet device, a music player, a tablet computer, alaptop computer, a netbook computer, an ultrabook computer, a personaldigital assistant (PDA), an ultra mobile personal computer, etc.), adesktop electrical device, a server or other networked computingcomponent, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a vehicle control unit, a digital camera, adigital video recorder, or a wearable electrical device. In someembodiments, the electrical device 1800 may be any other electronicdevice that processes data.

The following paragraphs provide various examples of the embodimentsdisclosed herein.

Example 1 is an electronic component, including: a tunneling fieldeffect transistor (TFET), including a first semiconductor materialhaving a p-type conductivity, a second semiconductor material having ann-type conductivity, a channel material at least partially between thefirst semiconductor material and the second semiconductor material,wherein the channel material has a first side face and a second sideface opposite the first side face, and a gate above the channelmaterial, on the first side face, and on the second side face.

Example 2 may include the subject matter of Example 1, and may furtherspecify that the first semiconductor material and the secondsemiconductor material are above a substrate.

Example 3 may include the subject matter of Example 2, and may furtherspecify that the substrate includes crystalline silicon or crystallinegermanium.

Example 4 may include the subject matter of any of Examples 2-3, and mayfurther specify that a buffer material is on the substrate, and thefirst semiconductor material and the second semiconductor material areon the buffer material.

Example 5 may include the subject matter of Example 4, and may furtherspecify that the buffer material includes a group III-V material.

Example 6 may include the subject matter of Example 5, and may furtherspecify that the buffer material includes gallium, arsenic, antimony,indium, phosphorus, aluminum, aluminum arsenide, aluminum antimonide,gallium arsenide, gallium antimonide, indium phosphide, indium galliumarsenide, aluminum gallium arsenide, indium aluminum arsenide, aluminumarsenic antimonide, aluminum gallium antimonide, indium galliumantimonide, or gallium arsenic antimonide.

Example 7 may include the subject matter of Example 4, and may furtherspecify that the buffer material includes germanium or silicon.

Example 8 may include the subject matter of any of Examples 4-7, and mayfurther specify that the channel material is on the buffer material.

Example 9 may include the subject matter of any of Examples 4-8, and mayfurther specify that the channel material is on an oxide material.

Example 10 may include the subject matter of Example 9, and may furtherspecify that the oxide material is on the substrate.

Example 11 may include the subject matter of any of Examples 4-10, andmay further specify that the channel material is between the firstsemiconductor material and the buffer material, and the channel materialis between the second semiconductor material and the buffer material.

Example 12 may include the subject matter of any of Examples 2-11, andmay further specify that a portion of the channel material is betweenthe first semiconductor material and the substrate.

Example 13 may include the subject matter of Example 12, and may furtherspecify that the channel material is not present between the secondsemiconductor material and the substrate.

Example 14 may include the subject matter of Example 12, and may furtherspecify that a portion of the channel material is between the secondsemiconductor material and the substrate.

Example 15 may include the subject matter of any of Examples 12-14, andmay further specify that a height of the channel material under thefirst semiconductor material is greater than a height of the channelmaterial under the gate.

Example 16 may include the subject matter of any of Examples 12-14, andmay further specify that a height of the channel material under thefirst semiconductor material is less than a height of the channelmaterial under the gate.

Example 17 may include the subject matter of any of Examples 2-16, andmay further specify that a portion of the channel material is betweenthe second semiconductor material and the substrate.

Example 18 may include the subject matter of Example 17, and may furtherspecify that the channel material is not present between the firstsemiconductor material and the substrate.

Example 19 may include the subject matter of any of Examples 17-18, andmay further specify that a height of the channel material under thesecond semiconductor material is greater than a height of the channelmaterial under the gate.

Example 20 may include the subject matter of any of Examples 17-18, andmay further specify that a height of the channel material under thesecond semiconductor material is less than a height of the channelmaterial under the gate.

Example 21 may include the subject matter of any of Examples 1-20, andmay further specify that the first semiconductor material comprisessource material and the second semiconductor material comprises drainmaterial, or the first semiconductor material comprises drain materialand the second semiconductor material comprises source material.

Example 22 may include the subject matter of any of Examples 1-21, andmay further specify that the channel material has a top face and abottom face opposite the top face, and the gate is on the top face andthe bottom face.

Example 23 may include the subject matter of any of Examples 1-22, andmay further specify that a height of the first semiconductor material isdifferent from a height of the second semiconductor material.

Example 24 may include the subject matter of any of Examples 1-23, andmay further specify that a height of the channel material is differentfrom a height of the first semiconductor material.

Example 25 may include the subject matter of any of Examples 1-24, andmay further specify that a height of the channel material is differentfrom a height of the second semiconductor material.

Example 26 may include the subject matter of any of Examples 1-25, andmay further specify that the channel material includes gallium, indium,arsenic, indium gallium arsenide, or indium arsenide.

Example 27 may include the subject matter of any of Examples 1-26, andmay further specify that the first semiconductor material includesgallium, antimony, indium, arsenic, gallium antimonide, indium galliumarsenide, or indium arsenide.

Example 28 may include the subject matter of any of Examples 1-27, andmay further specify that the second source drain material includesgallium, phosphorous, arsenic, indium, indium arsenide, indium galliumarsenide, or indium phosphide.

Example 29 may include the subject matter of any of Examples 1-28, andmay further specify that: the first semiconductor material includesindium, gallium, and arsenic; the second semiconductor material includesindium, gallium, and arsenic; and the channel material includes indium,gallium, and arsenic.

Example 30 may include the subject matter of any of Examples 1-28, andmay further specify that: the first semiconductor material includesgallium and antimony; the second semiconductor material includes indiumand arsenic; and the channel material includes indium and arsenic.

Example 31 may include the subject matter of any of Examples 1-28, andmay further specify that: the first semiconductor material includesindium and arsenic; the second semiconductor material includes indiumand phosphorous; and the channel material includes indium, gallium, andarsenic.

Example 32 may include the subject matter of any of Examples 1-28, andmay further specify that the first semiconductor material, the secondsemiconductor material, and the channel material includes a same groupIII-V material.

Example 33 may include the subject matter of any of Examples 1-28, andmay further specify that the first semiconductor material, the secondsemiconductor material, and the channel material include silicon.

Example 34 may include the subject matter of any of Examples 1-28, andmay further specify that the first semiconductor material, the secondsemiconductor material, and the channel material include germanium.

Example 35 may include the subject matter of any of Examples 1-34, andmay further specify that the gate includes a gate dielectric and a gateelectrode.

Example 36 may include the subject matter of Example 35, and may furtherspecify that the gate dielectric is a multilayer gate dielectric.

Example 37 may include the subject matter of any of Examples 35-36, andmay further specify that the gate electrode includes multiple metals.

Example 38 is a method of manufacturing a tunneling field effecttransistor (TFET), including: forming a fin of semiconductor material;forming a gate on top and side surfaces of the fin, wherein the gateincludes a first side and an opposing second side along the fin; forminga p-type material region, wherein the p-type material region isproximate to the first side of the gate; and forming an n-type materialregion, wherein the n-type material region is proximate to the secondside of the gate.

Example 39 may include the subject matter of Example 38, and may furtherspecify that forming the p-type material region and forming the n-typematerial region includes: removing a first portion of the fin to form afirst recess proximate to the first side of the gate; removing a secondportion of the fin to form a second recess proximate to the second sideof the gate; growing an n-type material in the first recess and in thesecond recess, wherein the n-type material in the second recess is then-type material region; masking the n-type material region; removing then-type material from the first recess; and growing a p-type material inthe first recess, wherein the p-type material in the first recess is thep-type material region.

Example 40 may include the subject matter of any of Examples 39, and mayfurther include, after removing the n-type material from the firstrecess, increasing a depth of the first recess, wherein the p-typematerial is grown in the first recess after increasing the depth of thefirst recess.

Example 41 may include the subject matter of Example 38, and may furtherspecify that forming the p-type material region and forming the n-typematerial region includes: doping a first portion of the fin with ann-type impurity to form the n-type material region; and doping a secondportion of the fin with a p-type impurity to form the p-type materialregion.

Example 42 may include the subject matter of Example 38, and may furtherspecify that forming the p-type material region and forming the n-typematerial region includes: removing a first portion of the fin to form afirst recess proximate to the first side of the gate; removing a secondportion of the fin to form a second recess proximate to the second sideof the gate; growing a p-type material in the first recess and in thesecond recess, wherein the p-type material in the second recess is thep-type material region; masking the p-type material region; removing thep-type material from the first recess; and growing an n-type material inthe first recess, wherein the n-type material in the first recess is then-type material region.

Example 43 may include the subject matter of Example 42, and may furtherinclude, after removing the p-type material from the first recess,increasing a depth of the first recess, wherein the n-type material isgrown in the first recess after increasing the depth of the firstrecess.

Example 44 may include the subject matter of any of Examples 38-43, andmay further specify that forming the fin of semiconductor materialincludes: patterning a crystalline semiconductor material to form aninitial fin; providing a shallow trench isolation (STI) material aroundthe initial fin; removing at least some of the initial fin to form atrench in the STI material; and providing a semiconductor material inthe trench to form the fin of semiconductor material.

Example 45 may include the subject matter of any of Examples 38-44, andmay further specify that the fin of semiconductor material includes alayer of indium gallium arsenide on a layer of gallium arsenide.

Example 46 may include the subject matter of any of Examples 38-44, andmay further specify that the fin of semiconductor material includes alayer of indium arsenide on a layer of gallium antimonide.

Example 47 may include the subject matter of any of Examples 38-44, andmay further specify that the fin of semiconductor material includes alayer of indium gallium arsenide on a layer of gallium arsenicantimonide.

Example 48 may include the subject matter of any of Examples 38-44, andmay further specify that the fin of semiconductor material includesgermanium.

Example 49 may include the subject matter of any of Examples 38-44, andmay further specify that the fin of semiconductor material includessilicon.

Example 50 may include the subject matter of any of Examples 38-44, andmay further specify that the fin of semiconductor material includes alayer of a semiconductor material on an oxide material, wherein thesemiconductor material includes a group IV material or a group III-Vmaterial.

Example 51 is a computing device, including: a die including a tunnelingfield effect transistor (TFET), wherein the TFET includes a firstsemiconductor material having a p-type conductivity, a secondsemiconductor material having an n-type conductivity, a channel materialat least partially between the first semiconductor material and thesecond semiconductor material, wherein the channel material has a firstside face and a second side face opposite the first side face, and agate above the channel material, on the first side face, and on thesecond side face.

Example 52 may include the subject matter of Example 51, and may furtherspecify that the computing device includes a power supply that providesa supply voltage that is less than 0.5 volts.

Example 53 may include the subject matter of any of Examples 51-52, andmay further specify that the first semiconductor material has adifferent height than the second semiconductor material.

Example 54 may include the subject matter of any of Examples 51-53, andmay further specify that the computing device is a mobile computingdevice.

Example 55 may include the subject matter of any of Examples 51-54, andmay further specify that the computing device is a wearable computingdevice.

Example 56 may include the subject matter of any of Examples 51-55, andmay further include a touchscreen display.

Example 57 may include the subject matter of any of Examples 51-56, andmay further specify that the TFET is included in a metallization stackof the die.

Example 58 may include the subject matter of any of Examples 51-56, andmay further specify that the first semiconductor material comprisessource material and the second semiconductor material comprises drainmaterial, or the first semiconductor material comprises drain materialand the second semiconductor material comprises source material.

1. An electronic component, comprising: a tunneling field effecttransistor (TFET) comprising: a first semiconductor material having ap-type conductivity, the first semiconductor material having a top faceover a substrate, the top face of the first semiconductor material afirst distance from the substrate, a second semiconductor materialhaving an n-type conductivity, and a channel material at least partiallybetween the first semiconductor material and the second semiconductormaterial, wherein the channel material has a top face over thesubstrate, the top face of the channel material a second distance fromthe substrate, the first distance greater than the second distance. 2.The electronic component of claim 1, further comprising a gate above thechannel material.
 3. The electronic component of claim 2, wherein thegate is on a first side face of the first semiconductor material and asecond side face of the second semiconductor material.
 4. The electroniccomponent of claim 1, wherein the second semiconductor material has atop face over the substrate, the top face of the second semiconductormaterial a third distance from the substrate, and the third distance isgreater than the second distance.
 5. The electronic component of claim4, wherein the third distance is the same as the first distance.
 6. Theelectronic component of claim 4, wherein the third distance is greaterthan the first distance.
 7. The electronic component of claim 1, whereinthe substrate includes crystalline silicon or crystalline germanium. 8.The electronic component of claim 1, wherein a buffer material is on thesubstrate, and the first semiconductor material and the secondsemiconductor material are above the buffer material.
 9. The electroniccomponent of claim 8, wherein the buffer material includes a group III-Vmaterial.
 10. The electronic component of claim 8, wherein the channelmaterial is on the buffer material.
 11. The electronic component ofclaim 1, wherein a portion of the channel material is between the secondsemiconductor material and the substrate.
 12. The electronic componentof claim 11, wherein the channel material is not present between thefirst semiconductor material and the substrate.
 13. A computing device,comprising: a die including a tunneling field effect transistor (TFET),wherein the TFET comprises: a first semiconductor material having ap-type conductivity, the first semiconductor material having a top faceover a substrate, the top face of the first semiconductor material afirst distance from the substrate, a second semiconductor materialhaving an n-type conductivity, and a channel material at least partiallybetween the first semiconductor material and the second semiconductormaterial, wherein the channel material has a top face over thesubstrate, the top face of the channel material a second distance fromthe substrate, the first distance greater than the second distance. 14.The computing device of claim 13, wherein the computing device includesa power supply that provides a supply voltage that is less than 0.5volts.
 15. The computing device of claim 13, wherein the TFET isincluded in a metallization stack of the die.
 16. The computing deviceof claim 13, further comprising a gate above the channel material. 17.The computing device of claim 16, wherein the gate is on a first sideface of the first semiconductor material and a second side face of thesecond semiconductor material.
 18. The computing device of claim 13,wherein the second semiconductor material has a top face over thesubstrate, the top face of the second semiconductor material a thirddistance from the substrate, and the third distance is greater than thesecond distance.
 19. The computing device of claim 18, wherein the thirddistance is the same as the first distance.
 20. The computing device ofclaim 18, wherein the third distance is greater than the first distance.